Strangely, I tend to play casually, and that's what gets me to quit. I'm never "Good" so I never go on Raids, etc.
I still enjoy checking the games out though. Played WoW for a while.. "somewhat less casual" for a while.
I'm probably done with it forever at this point, but never know. I kind of want to try Age of Conan and Warhammer Online.. Who knows. I'll probably wait til you can get the game cheaper.