I really like how Wildstar is looking, and its the first MMO in a long time that I've really considered. But the big issue is, again, time. Not just 'time' but.. well.
Lets say I get 10 "Happiness" per hour from WoW. And I can allocate 4 hours a day to playing games. So I currently get 40 points a day of self fulfillment.
Lets say I get 9 from Wildstar. I still love the game, and enjoy playing it, but I know that I could have been slightly better off playing WoW. Would I still be stoked? Yeah. But I'd feel like I was losing out by not playing WoW.
Same thing with me and EVE. The time committment for both is hard. It's not the money (though that is a factor).
Not just that, but the time with my friends. If they're all playing WoW, I'll probably want to play that, no matter how much I might enjoy another game. Or, I might enjoy another game that they play, but that means that me, and 2 or 3 other people all have to coordinate our time together, which can be a hassle on logistics. Especially if you're in different time zones.
So time is the issue, but for different reasons.