The best way to deal with that is to see a new expansion as a new game altogether. What I enjoyed during Vanilla isn't the same thing I enjoyed in BC, etc. Right now, with Draenor, I'm having fun with Garrison which is a kind of Farmville where you can hire NPCs going on mission for you, have NPCs crafting and gathering for you. I never thought that would be the thing I'd enjoy in the game, and have I read about that pre-release keeping in mind what I enjoyed doing then, I would have questioned Blizzard for including this in the game.