"Uh... few different reasons." he pauses, thinking over how to put this for a few seconds.

"Mostly, it's 'cuz nudity is associated with sex. Hell, some people get off on being seen naked by strangers, so others might feel like they're being forced to get involved in another person's sex life in a way they didn't want to be. And, even if that's not the case, people may just not want to see a stranger's body, especially when they're not expecting it."