I'd imagine that at the time, this sort of music and the fads/styles it inspired were threatening to overly paranoid and inflexible parents, much in the way hip

I'd imagine that at the time, this sort of music and the fads/styles it inspired were threatening to overly paranoid and inflexible parents, much in the way hip hop, baggy/saggy pants, and other symbols of "degraded" culture are seen more recently... ...which, of course, is a large part of the appeal to younger folks who are drawn to things that are decidedly set apart from (or contrary to) the culture and styles of their parents. I remember when I was a teenager, I really did like a lot of the music and styles of the grunge/alternative trend, but in retrospect, I'm sure a big part of it was that it was specifically not what my parents identified with so it felt more like something of "ours". The whole cultural identifier thing works both ways when it comes to signaling in-groups and out-groups. Choosing to set yourself apart from where you originate is on some level a rejection of that origin and can be either a gesture of independence and strength or an attack on what someone else holds to be valuable.