Sadly, it appears(at least from my perspective) that IP means very little in MMO's. Galaxies was popular from the start thanks to it's pedigree but it sounds like it got run into the ground. The Matrix? Uh, let's not go there. The Sims? An abysmal failure considering how wildly popular it was *supposed* to be.

Like many have said before, IP will get people in the door but it has almost nothing to do with making them stay. Two of the most popular MMO's of all time had, to my knowledge, no previous IP to begin with: Evequest, Dark Age of Camelot. Yeah, yeah both are based either loosely or very much on classic high fantasy elements present in fiction or pen and paper RPG's, but we're not talking about IP that was served up on a silver platter. They created what made them popular and most of that was gameplay.

Marvel, DC, Disney, Warner Bros., Lucas Arts, and the list goes on. Where are the wildly successful MMO's from those IP warehouses? IP gives you backstory and some fans. Gameplay is what catapults you to the top.