Wow you really don't get it. Allied races are sub races, just look at what they added - ALL 6 "allied races" are models already available to players, just slightly altered. If they wanted to add Ogres or Vrykul they would just add them as new race, like Worgen or Goblin, since these are new models.
Otherwise what was the reason to add new races as "allied races"? God some people just make no sense.