It evolved. While some "Money, Cash, B!7c#**" songs do exist, what makes that so different from the "Sex, Drugs, Rock'n'Roll" songs of hair metal bands. A lot of rap is shallow and stupid. So is a lot of non-rap music. As long as there has been a lowest common denominator, music has been made, in all genres, to exploit them. Are you honestly going to tell me that this
is better than this?:
Now, for some rap music with the emotional intensity to make me actually cry.