I'm not judging anyone for playing WoW, I think it is a great game, and a very succesful franchise. My main gripe with it was that it seemed to be redundant.
Every 4-5 months, just as you got all the gear you could in arena/raiding, they come out with new content and a new tier of gear and the grind starts all over again. It was honestly a never ending circle. And the nature of the game is that you can't just pick it up and play a couple of matchmaking games, then go to bed.
You have to be able to sit down and clean your schedule for a good 4-5 hours if you want to get raiding/arena done. Even then, getting your gear is not gauranteed due to different loot methods, and the fact that you could spend 4 hours getting to the boss that drops your piece of gear, it doesn't drop, and now you have to come back next week for the same thing, then it drops next week and the guy who is infinitely worse than you at WoW wins the roll and continues doing 2 k dps. Fun.
I just couldn't rationalize paying money anymore for something that took up so much of my time. A gym membership where the only benefit was shiny purple lootz and the drawback was a PO'd fiance and less sexy time. Thats just my personal experience with wow