Though the idea is cool, but the models can't be made form "scratch" scratch. They have guidelines to follow. Pandaren is the level of customization to achieve, but not surpass, that would make the pandaren obsolete as well.
---------- Post added 2012-12-24 at 06:37 AM ----------
Yeah, I think as well that sliders are out of the question given how the models work. The only viable option would be different models for body types.
---------- Post added 2012-12-24 at 06:39 AM ----------
This! facepaint for trolls and tattoos for night elves, as separate features.