I am an African American male and I can honestly say that most of the time when I go places, I am the only black person I see, or one of the very few.
I think most of it has to do with religion/culture that most black people embrace. I hate tracing things back like this, but religion is so important to a lot of black families, something that had been instilled from slavery, segregation, etc. that most won't stray or question it. From that, nudity becomes this sexual thing which your entire family frowns upon. You're only supposed to be naked when you're washing, and with your love. That's it. Otherwise you're being inappropriate and someone has to set you straight. As far as younger kids go, most youths are in not so great areas that promote how cool/popular you are by the things you own, especially clothes. When I was growing up it was important to have the brand new jordans, all the matching clothes, all the name brands etc. Girls wouldn't talk to you if you didn't have the right gear, if you wore old stuff, or mismatched you got clowned on, and the better your clothes were the more people respected you. It's part of the hip hop culture. The emphasis is on things, not people. The focus is on getting money, and more especially what you can buy with that money. Having really nice clothes everyone knows about shows you have money and status just like that music artist. Then there's also gang related things where clothes are important signs of what gang you're affiliated with or who you're not with. I remember avoiding wearing reds and blues when I lived at home just to avoid problems and concentrated on blacks/whites/greys and random colors like green and purple. Of course this doesn't work for every black person in America, but it's definitely a reason why for some, especially if you look at the stats of religion/socioeconomic status.