I like open MMOs. Sandbox ones. I think a linear story-based approach is wrong for an MMO if you actually stop and analyse what an MMO should be.

It's weird because Tanaka always said that he wanted players to play in the same world (no instances) and, also, the old development team put a lot of emphasis on a player-driven economy... so they obviously thought that player-interactions were an important aspect of the MMO genre and philosophy. And yet for some reason they marketed the game as a story-driven MMO (!?). There's an irony there.

Linear stories are no place for an MMO where player-interactions can and should serve as substitutes.

In this sense, Bethesda have the right idea. Their games are more dynamic, and I'm sure an MMO with these game-design principles would be successful because it would play to the inherent strength of the MMO genre.

But, in saying that, I found Oblivion to be very boring as a single-player game. It's no fun playing that type of game by yourself.