Class design wasn't exactly great in WoD, destro locks, arcane mages, BM and MM hunters were all super easy to play and far too strong for their simplicity. Tanks especially at the end could do almost everything completely on their own monks, pallies and DK for example were all insanely strong and self reliant. On the healing side you had disc priest who could mindlessly spam attacks and still be a very solid healer in most cases, druids with their pre stacking of their mushroom had an on demand aoe lay on hands. There was a lot to be desired with WoD's design nevermind they did almost nothing in the game as far as game play went so the classes should have been very polished.