It started with Brian Green musing about something being missing in our MMOs, which was followed by Steve Danuser weighing in on the issue as well. The specifics are under debate, but there's been quite a bit of furor on the basis of that simple concept -- that something ought to be there that isn't. We've lost the sense of adventure, of the game and the story being epic. What is it? An interesting idea has been put forth on Fool's Age: perhaps what we're really missing is the opportunity to fail.
Leaving aside the inevitable string of comments about how it's possible to fail permanently in Champions Online by choosing the wrong build, there isn't a way in most games these days to undertake a quest and fail. For that matter, it's not even usually possible to alter the course of events -- you might recognize two steps in that the kindly old man is not who he says he is, but you still have to complete the quests as they're offered. The entry discusses some of the obvious problems with allowing players to permanently fail, but the question bears examination. Would our games be better if we had the very real threat of screwing up and failing permanently?