Have you ever taken a second to think about why you dress the way you dress? We don't mean when you're at work, where you might be required to wear a uniform or dress to a particular style, but the way you dress when you're at home. Unless you're a free spirit, you probably wear similar clothes to your friends, and the other people around you. It may not always have been that way; you might have been a punk or a goth when you were a teenager, but eventually you settled into a fairly standard style, probably influenced by societal norms.
Children have no such limitations. If they want to wear a neon pink t-shirt with orange shorts, they're going to do it. If they want to wear a dress covered in glitter to go to the shops, then that's what they're going to do. Accepted or normal styles of wearing clothes haven't occurred to them yet, so let them express themselves however they like. Even if it does hurt your eyes!