I support, especially with V3 coming up. I pretty much hate the theme previews I've seen of it. I'm probably never going to like anything but V2's layout, but having the option of changing the colors and theme to something that isn't as much of an eyesore to me would make things a little better.
I used to love the themes Nutrinopets offered, if anyone remembers that. I liked quite a few of them, and could change them based on my mood or preference at that time.
Style switchers aren't that hard to make, and, from what I've seen, are pretty basic to anyone with some programming knowledge. I see no reason why Res wouldn't/shouldn't add this. :3