The R-P-S argument is not generic nonsense. That is straight from Blizzards mouth. Not every class, or even class spec is balanced against each other. There have been and always will be classes than will, all things being equal, beat some and lose to others. This is by design. So to answer your question, no they do not have a reason to complain. If Blizzard wants to make Blood the PvP spec of choice and leaving Frost and Unholy not particularity viable then so be it for this iteration of WoW.