People who make posts like this always gloss over the fact that pure dps classes have defensive abilities or self-heals as well.every tree for a rogue is based around dps. every tree for a mage is based around dps. even War's more or less have tanking/damage trees only. you might have a point about Priests/Shamans but i didn't bring them up in the pure examples i made, especially since blizzard gave all healers damage a while back.
thing is resto druids can shift to bear and soak damage, don't tell me they have to spec for tanking to do that. ferals can lay hots on themselves, they don't have to spec resto to do that. they might not be able to do it as efficiently as if they are specc'd for it, but they can still be a jack of all trades in WAY more areas than most other pure specialized classes can, which is why they should never be able to out dps the pure's. it just doesn't make sense to give a class that can do a little bit of everything top dps over classes that are supposed to be specialized in dps, and thats basically what all of their trees are centered around.
blizzard does a lot of stuff that isn't really even(look at racials) so common sense doesn't really apply to their game design so much, but looking at it from a reasonable and fair/balanced standpoint, ferals should never be outdamaging pure dps classes, ever.
just to add free movement in WoW PvP is probably the most important factor to it.