I think it was indeed the change of an era for many people.
I always thought it was kind of strange when people labeled The Offspring (which was just 'Offspring' back then, if I recall correctly) as being punk. I've always considered it to be a little too soft to be punk.
I think a lot of the 'darker' music did the same for many people: making them realize they were not the only one feeling/thinking like that.
For me, that happened when I was introduced into the psytrance scene. The music, and all the people and their values that were attached to it, made me feel like I wasn't the odd man out for the first time in my life. We were/are all outcasts and had been different from other people for all our lives, but together, we are all the same.
Gosh, it is so hard to explain. Writing part 2 will be hard work to make sure the message comes across.