Everybody blames AP grind, but don't forget absurd rise of wowtoken prices. We've lost at least three people due to that particular change. (Got myself a free Overwatch and three free character race rerolls, though, so not complaining, but still...)
Also: IMO, absurd amount or RNG layers is way worse than AP grind. That particular feeling, when you and your friend raid together, both are same spec of a same class. But you get prydazes and common gear, while he get top legendaries and titanforged socketed gear. He even gets a 920 stat stick trinket from worldquest with his best secondary stat and a socket... That sucks so much. So much...