Actually, that is exactly how language evolves and that is something that occurs whether people think they have the right to do so or not.
I'd buy that ****boy originally meant
but we'll see where "white girls" take it.
To an extent, yeah. In the same sense one might say the word "nice" has evolved through-out the ages (it used to mean stupid; "nice guys finish last", etc... ). But you're thinking in a much more general sense than what it actually is - this is slang. It's suppose to be hip and up-to-date. If you don't use it right and get called out for it you can't just say "words change over time" as an excuse.