Mainly, raids where/are boring/exhausting, too much time killing/trying to kill boss's. after vanilla my "wow played time was to arenas only and some bgs. And got plenty of time in my hands to do other stuff, basically in cataclysm just played about 4/5 months, the first was to lvl and wait for the pvp season and the last 1/2 months where boring already.
Only got tired of pvp in cataclysm, nothing new (rated bgs suked alot) but i got tired of PVE looooonnnnnng time ago (end of vanila)
So, unless another blizzard/wtv company would offer a new gaming experience i dont wanna play a MMO again.. not interested in clones.
For diferent talents and dif class fixs the wow patchs where enough or else i would got bored really sooner.