Personally, I like the idea of controlled customization - admin provides a limited scope of control, like a few templates/layouts and allows personalization of elements that wouldn't disrupt the page no matter what the user comes up with. To even make this possible we're rebuilding the default template, making it image-free and highly unified. This would create a certain window of opportunity that can be relayed to users in a shape of profile customizer. Twitter, for one, is a good (albeit a bit see more extreme) example: they will let you change the background and colors a bit - but whatever you do, you can't brake your profile.