Why replace the old models?

Why replace the old models? Why not just add to them, and put full customization in the barbar shop (with a long CD, paying $$ can shorten the CD), and thus make this whole thing optional. 1) You will never satisfy everyone if you force them to change the look of their character, even if the new look is "better." 2) Adding new models, instead of replacing the old ones, means you are not limited by the creative roadblock of having to make them close to the old models.
World of Warcraft(EUR)
Just like how you are not getting rid of outland, but building a new one. I really thought you had learned your lesson with Cata, we don't want revamps, we want the new AND the old - and we want the old to stay the way it is.