"It simply wasn’t the focus for us this time around," Miyamoto said of online play. Though it was a possibility, the development team "really wanted to do was to create something that people could experience fully while playing comfortably with others who were nearby them," as was also the case with Pikmin 3.
"Now that is to say the answer to this question might change in ten years time," the living legend continued. "If there’s a future game where for example we don’t think it’s important to be able to see the face of the person you’re playing with, then we might be able to focus more on some online function there. But for right now our focus is really on a comfortable play experience with people in the same room."
Ugh. So we may have to wait until 2023 to play online co-op in a Mario game, because the developers simply didn't feel like putting in the effort. A lot of gamers work full time, and a lot of us who have family around don't game, and a lot of us who have gaming friends know those friends, well, online. It's cool that they have multiplayer working in both traditional and more modern design style Mario games, but it would sure be nice if they would stop denying so many of us the ability to actually use that multiplayer feature.
Eventually, they have to come to terms with the idea that sometimes they will have to give consumers what they want, instead of always trying to give them what they THINK they want. Or just doing what they feel like doing, consumer be damned. It's this kind of thinking that cost them their leadership of the gaming market in the first place. They need to reign in Miyamoto and his people, because at some point, someone within the upper echelon should have grown a pair, stepped in, and said "this must have online co-op".