I had another post of full mirror racials.
You seem to dislike particular race/class combo idea. True, noone is going to take paladins from humans or give em to Forsaken, but in Wrath paladins had EMFH ability more powerfull and broken, than current WotF.
And Horde paladins still have AoE silence that no Alliance paladin can get even with my full Mirror racials idea. Same goes with druids and other classes.
To achieve ideal class+race balance you need to add combinations that were not introduced even with Cataclysm.