you know what premium users should get

Well it could be a total crock, but I think one of the reasons most games (mainly on console anyways) don't support a map editor is because of the complications that come from it (building the system that allows you to make the map using only a controller instead of how it's actually built by the developers on their computers). But like I said it's probably a total crock. I know the main reason for sure is because the companies involved lose cash since no one would really buy map packs when the consumer can create superior maps.

Yet you look at games that support user content and see that they live LONG after their expiration date. Blizzard games are proof of this. Starcraft is over ten years old and people still play it (maybe not as much now with 2 out but still) simply because of all the maps that you can create. It was also one of the main draws for me when I bought Far Cry on the original Xbox, loved the editor and spent countless hours messing with it.

The only draw back with user created maps are all the stupid ones people make so that when they're playing they'll always have the upper hand because they'll make cheap sections (racers having that section or two that if you take it you have like a 30sec lead, typical shooters with their stock pile of super weapons, etc) that a single person would be able to typically dominate in.

Though I hope when Mirror's Edge 2 comes out DICE adds an editor or at least a free roam mode so you can just run around doing what you want instead of being stuck in a linear system.