If you think about it, we're just animals. It's really crazy that we can't just walk around in our natural state freely because we tend to feel really weird about looking at other members of our own species.
What if I've got it backwards and other animals are just as prudish? When a dog is barking at another dog, maybe he's really saying, "hey, check out this weirdo - he's naked! Get the hell out of here, you pervert!"
http://gizmodo.com/5627807/bubbling-tricks-your-mind-to-make...
Link is technically safe for work but looks NSFW (that being the entire point of the illusion)
But yes, this apprehension of nudity is something I've always found so bizarre. Why is seeing skin of our species such a big deal? At what point of our social evolution did it evolve that way (because the idea of clothing is pretty universal to humans).
Whoa, whoa, whoa.... whoa. I like to think of myself as open-minded but I'm not ready for that just yet. That being said, San Francisco apparently has no punishment for being nude in public and yet I've only seen nudity in public twice in the 6 years of having a full-time job there. So maybe it should be removed from the law and most people will continue to cover-up out of personal modesty.