| They dumbed it down and removed all the challenge or depth. Although they did keep the raids, which were the worst part of the EQ endgame.
Less snarkily, WoW attracted a lot more casual players, who recruited their casual-gamer friends. The longevity of these games depends on the social networks that arise -- the more people who have an attachment to and play with on a regular basis, the less likely you are to stop playing entirely or hop to another game.
Having played pretty much every MMO since Ultima Online to max (or close to it), WoW is probably the one I've liked the least, and even I feel the tug to return occasionally simply because of the friends I have that play it.
What sucks is that every potential MMO developer now feels that they have to achieve WoW-levels of subscribers to be considered a success, so we're starting to see the same repeition and type of formulaic crap in the MMO market that you see in other forms of mass entertainment. I suspect my days of hard games with meaningful death penalties, actual travel and exploration, etc., are long gone. | 
And yet another word from our sponsors
