I can understand this reasoning, but is it really the case? In practice does anyone actually stick to HTC or Motorola because of their skins?

I know that the feedback I usually hear has a huge selection bias in this regard (almost all techies) which is why I'm asking the question.

Even considering the selection biased, I'd be surprised if people preferred these skins. I think that people who are aware of these skins, and the options out there, probably don't like them. If they're not aware of them then they can't prefer them, right?