Raph Koster has an interesting post on his blog speculating that the 'virtual world' MMORPGs where immersion and roleplay were the ultimate goal is a thing of the past. I think he's right -- it seems that more 'game-y' MMOs (often called 'theme-park style games) are the new norm.
I think this is plain in the generation gap that is visible among MMO players nowadays -- the 'oldschool' player who wants an MMORPG with deep lore to follow, and a world they can lose themselves in and feel a part of. These types are largely derided by the 'new wave' of theme-park gamers who scorn those that RP, or care about lore, or who express a desire for more 'immersion' and game mechanics that encourage a 'fantasy life' experience. The oldschoolers want avatars that are detailed and highly customizable so that they can create a representation of themselves that has a deeper personal meaning; the new generation sees avatars as simply 3D mouse cursors that are used to interact with the game environment.
The oldschoolers scorn the entire idea of a 'themepark ride on rails' with 'shallow worldbuilding'. They are disappointed in most modern MMORPGs because the concept of a 'virtual fantasy world that you can pretend to live in' is not what the modern MMORPG is about.
Related Link: The rise of RMT and the decline of RP in MMORPGs