that has nothign to do with concept and classes
it's just blizz is unabe to balance it, some examples: 2h windfury and 2h frost just destroyed everything in pvp iirc while in pve dw was stronger
also look at the dk: they had 3 tank and 3 dps but thanks to balance issues not all 3 tank/dps were good enough in pve if they could do it dk would still have 3 tank and 3 dps specs
I mean look at current spec some are just over/under tuned, blizz is just unable to balance classes and that has NOTHING to do with new classes this is a 13 year old problem