What exactly makes us think that we have any say in what other people wear?

I did get this from the teenagers and piercings question, though I’ve seen similar comments come up so many times in other discussions about tattoos and piercings. People will express that some people “just can’t pull it off” or “shouldn’t wear this or that.”

I also see this mentality often when regarding a heavy person wearing tight or revealing clothing. Particularly women. And often just women in general, for example: “What was she thinking when she put that on this morning?”
Right away, my own thought is that if it isn’t hurting anyone, why should we care?
We have tons of makeover shows on TV, magazines are constantly printing articles about what you shouldn’t wear… but seriously, now, why is it any of our business what other people are doing with their own bodies?

Of course we all have preferences. Some things are attractive to us and some things are not, but I really think it goes beyond that. What is it about society and our, dare I say it, obsession with how everyone around us looks?