I'm not asking for a revolution personally.
I'd settle for a challenge.
I want, whether solo or in group, that when I stand before a mob my level to have to evaluate and think whether I want to engage it or not, because engaging it means one of two outcome...it dies, or I die, and I should care very much about not dying because it should suck.
Now dying means nothing it's merely an inconvenience, and often not even that.
In today's game, you engage a mob, accidently aggro 5 mores, and you just run for 5 seconds and the mob leashes and resets leaving you safe and sound.
I'd settle for WoW being challenging, I remember it was somewhat challenging in Vanilla. You'd die quite often just adventuring solo, where you aggroed too much, or aggroed an elite(remember when elites were actually hard). And WoW was never really that hard but it was better than what it is today.
Just bring that back, where the game isn't a walk in the park and where failure means something and it is to be avoided. Just that and I think we would be at decent place.