I used to be a hardcore MMO fan. I played basically everything on the market from Final Fantasy XI, Ragnarok Online, World of Warcraft, Warhammer Age of Reckoning, and so on. MMORPGs, or massively multiplayer online games, used to be a powerful market that drove backbones of companies as relatively safe but steady revenue streams. They became mainstream in the years and especially the two expansions following World of Warcraft. In recent years, however, the profitability of MMOs has declined tremendously to safe, yet time consuming levels. An MMO is still a relatively safe investment for a developer, but they require an investment on par or usually greater than a modern AAA title and will only recoup their investment over a series of years relying increasingly on microtransactions rather than subscriptions. They are no longer the free money that publishers relied on for more risky ventures. What changed?
The biggest reason I can consistently see MMO's failing is their community. The actual community is just like any other game community: a mixed bag of personalities and degrees of seriousness. The community I'm referring to is the vocal community, the ones that play the betas and post on the official forums. Game developers rely heavily on consumer feedback, but in the case of an MMO that feedback can be realized in a patch rather than a sequel. Let's be real here: the people by and large providing this feedback are the ones that take video games seriously. The ones that don't understand what is so difficult about pulling off a 32 hit combo in Mortal Kombat 9 and post on IGN forums about how "casuals" are ruining their IP's then pay top dollar to personally attend Blizzcon in full Night Elf make-up. These community members in an MMO setting often have a staggering sense of entitlement and are very vocal about it. It's not just that they feel entitled to regular content updates as any subscriber should, but they usually feel that these content updates should be catered specifically for them and anyone who can't handle what they want can continue to pay their subscription for no content updates. If there is a quality of life change in the game that removes redundant or unnecessary mechanics, this is seen as "dumbing down" the game. This goes doubly for gearing and the demand for insurmountable power creep which I'll get into later.
A perfect example cropped up in a forum post on the Star Wars: The Old Republic forums, a thread that has been ongoing since mid-2013 about the inclusion of addons to their game. If you ask the average PC gamer if adding mods to a game is a good idea, you'll by and large get a resounding "yes!". Not so in the SWTOR community. The vast majority of posters insisted allowing addons would be the death of their favorite past-time and players should play the game the way it's meant to be played or not play at all. Basic features seen in other MMO's like mouse-over casting which makes healing roles require one less click while still being limited by a global cooldown or a boss mod that simply moves boss warnings to a position where it is more easily visible is seen as a "dumbing down". So the only voices heard by the devs are a community that wants mechanics that are inefficient and unnecessary because to them, dealing with bad mechanic design is what separates the "baddies" from the "goodies". SWTOR to this day does not have addons or even macros. It's population continues to dwindle and content updates are few, small, and irregular.
A similar situation occurred in Rift before Storm Legion and World of Warcraft in Mists of Pandaria caused by this hardcore community which leads me to the second major killer of MMO's: power creep. Power creep is when an established player takes a significant amount of time to reach a position of development in a game and participates in a content patch that is considered to be the only relevant content patch at the time, but a new player is excluded from the only content the community is interested in doing because they haven't put in the same amount of time as the veteran player. This can sound completely reasonable if you haven't been in this situation. So take WoW's tier 16, the Siege of Orgrimmar. Most guilds publicly recruiting for SoO require an item score equivalent to the Flexible difficulty of the dungeon, ilvl 540. Many of those require much higher, closer to 550, near the actual level of the content. A new player hitting the level cap arrives on the scene in about ilvl 430 gear. After running dungeons or grinding (spending large amounts of time killing things not for fun because you have to) the Timeless Isle a new player can work their way up to ilvl 496. This can be very time consuming and for an average player with real world responsibilities can take up to two weeks.
This means not including the time spent leveling their character they have spent $7.50 in old content trivialized by players hilariously over-geared for it, so they've spent most of this time in their multiplayer game soloing island monsters they don't have the equipment to efficiently kill or being carried and severely outperformed by established players. For them to work their way up to 540 from that point requires once-per-week loot from Looking for Raid instances, or if they're lucky have been referred to a website outside the game where they have to make an account and then be charitably carried again by other members of the community. This will take several more weeks. So at this time this new player has now spent a month or more and still can't participate close to the level of the established player not by skill, but by gear limitations. The hardcore members of the community will nonchalantly tell you to run the old normal modes, except virtually no one runs these modes anymore and when they do they require gear that vastly out-gears the content and achievements demonstrating you have already done them.
What made this system worse is the Legendary quest line. The Legendary Cloak and Legendary "Meta-gem" are special items with very potent effects that take months real-time to earn, probably three or four for the average player. Most "normal" difficulty guilds at this time require these items to be considered for application. So a new player trying to become a member of the WoW raiding community has a minimum of several months before his gear is developed enough to be brought in as a trial for your average raiding guild. In the meantime the guild has had to replace several veteran players who have burned out from running the same raid instance every week 12+ times. It sets up a system where the game literally loses players faster than it can replace them, and it depends on new players tolerating several months of being a social pariah before finally being accepted into the fold. When asked for systems to streamline player recruitment, the hardcore members feel this invalidates the work they've put into developing their characters and insist new players must spend as much time as they did to get to where they are after 9 months into an expansion. This has happened in virtually every MMO ever conceived.
In the past power creep was part of the price. MMO's were a niche market catered to by studios with special development teams who exclusively worked on the same game for years at a time. Now when an MMO budget is a make or break investment for a studio, developers continue to alienate more casual markets to cater to the hardcore community. Cataclysm and Mists of Pandaria have likely been the least beginner friendly expansions since Classic and are the only two expansions that have lost customers. As of MoP, WoW's subscriber base has declined from ~12 million to 7.7 million. Population declines have been seen in other games with severe power creep as well such as Rift and Aion.
The next issue facing modern MMO's is wholly on the fault of the developer. It's a lack of seriousness in developing MMO's. If there is a developer reading this their head just exploded, but let me explain. A typical MMO runs a subscriber about $15 a month. This means the average player can expect to run around $180 a year for their hobby. This is the price of three full priced AAA games. An MMO expansion varies by developer but runs anywhere from $15-40. Most developers get an expansion out once per year to two years. So the price per year of an MMO runs anywhere between $195-230 per year or nearly four full priced AAA games. Developers don't release even close to one AAA game of content per year but charge for three. When I can get two WoW's of content out of my Skyrim with mods for $60 (now much less), paying for an MMO seems like a poor investment to me that I only tolerate because I'm already a member of the community. A real professional doesn't make excuses about why they can't meet expectations then demand to be paid full price for their work. A real professional alters their pricing to account for them not meeting expectations. MMO developers these days don't even make the attempt to lower their subscription prices to be more attractive for the level of work they are willing or able to put in. In fact, they put their time and resources into microtransactions to milk more money out of their ever shrinking consumer base.
The last issue facing modern MMO's is also the fault of the developer, but specifically developers attempting to enter the market. The issue comes with robust leveling systems. Most MMO's these days have a scripted story of events that a player solo's their way through. Some feel this is the problem and those people are wrong. Requiring multiple people for leveling just means it's the same leveling system except if no one's on you can't progress to the only point the community cares about: endgame. So developers spend huge portions of their budgets, the vast majority, on robust leveling content that amounts of an honestly pretty mediocre, maybe even sub-par single player game experience. The only thing the community will be talking about 2 months from now is what they are doing at endgame in PvP or PvE. So developers focus all of their budget on temporary content players will play one time, maybe two times if they are really serious about it, then never play again. Meanwhile players leave in a mass exodus over a lack of endgame content because they feel like there's nothing to do now that they've made it there, or they don't even make it to level cap because it's the same slog they've done 15-16 times in other MMO's. The focus needs to be shifted away from leveling content and making the most robust (and bug free) endgame possible.
These are a lot of the primary reasons I see MMO's failing. World of Warcraft achieved market dominance by being the first developer to rewrite the laws of MMO's that dictate only those that spend the most time in our game are worthy to succeed. WoW forgot that they built their base around the little guy in the game and the rest of the market has followed suit. New entries to the market are consistently listening to only their hardcore members who demand releases without market standard features like dungeon finders, macros, and addon support. I don't see the MMORPG market outright dying, but a complete retraction to the old niche community is almost a certainty at this rate, and this has already happened for all MMO's except for WoW. As the niche market ages even that market is shrinking. A paradigm shift is inevitable and AAA developers are too scared of losing investments to attempt something new and interesting. I think the only hope for the MMO market is an indie developer with the stones (and cash) to take on an MMO project with fresh ideas that can attract casuals as well as hardcore.