I think it's not a good idea. If we need some personalization, we can create as admin 10/20 recolor of the basic skin, and offer the choice to the users.I have some idea.
We can add permission for groups. Example john is in registered groups. He can creating new style and he can use it. The other group members can't create new style style. And he can sent the new style to admin. Admin seeing and admin can aprove the style. After the other members can use this style.