Maybe it was the nature of it in the fist place. Um they were and are mostly protest songs against society, the system, poverty and important: authority. Hence there dislike of rap from the start. Hmm the swearing helps too.
On the other hand the wtbs had a thing against Rock 'n roll, blues Jazz and you name it. even the twist was banned I mean...C'mon! They are control freaks and this is just a symptom of that attitude. "we old farts don't like and so should you" kinda spirit.
Greven, Yo!