A lot of Rock was protest music. That people protesting at that time are now fat and happy. A lot of Hip-Hop is protest music. The people protesting have not reached the fat and happy stage yet. Is that true? No idea, but it sounds good!
Some people wonder why Country music still exists.
Music tends to morph, change, and intermingle. Look at Usher, brander R&B/Hip-Hop, but to me (I like the music), he sounds like a mashup of 80's synth-pop, 70's light rock, and 90's boy band, with the odd 90's rap to extend the audience.
@jerryg123 , I don't have to deride my kid's generational music. They do that themselves.