playing 10 minute guitar solos
Spoken like someone who has all the "I hate 80's music" attitude, but without being informed enough to use actual facts. 10 minute guitar solos are something you maybe hear in prog (I don't know as I cannot speak from experience), but certainly not 80's music. An average hair metal guitar solo is probably anywhere from 30 to 45 seconds. There might be an extended live solo, but Dream Theater did that for a very very long time also. Oh noes, excessive!
I agree Nirvana weren't influential because Kurt killed himself (though that undoubtedly helped their popularity carry on a lot further than it might have). Nirvana were influential for making it cool to not care about playing your guitar well. That's my opinion, but saying that simple guitar playing and simple songs are more relatable to people is BS. That would mean that nobody could relate to Dream Theater (to be fair, anymore, I can't relate to them). I don't imagine you'd agree that DT, despite their complexity, is relatable to people.
The ignorance and narrow mindedness about '80s music here is really sad sometimes, given how open minded people claim to be. Most '80s bands were all about writing short accessible songs, with maybe a little bit of flash in the solo to stand out, but the more popular ones were the tasteful and melodic ones. The bands like Nitro weren't the ones that made it to the top. And then people criticize hair metal for being simple. You can't win!
Hair metal wasn't all about partying and screwing by any stretch either. There were lots off equally relatable songs about the common stuff like relationships, life, hardship, etc.
Grunge was just the next fad, and record companies were only too happy to jump on the bandwagon and exploit it. Grunge didn't kill off hair metal, it barely even competed against it. There was very little overlap, and you can look up any hair metal band and the story is the same. The record companies only wanted their grunge, so unless you wanted to conform to the latest craze, you were essentially rock-blocked. The few bands that did release albums during the '90s sounded nothing like their '80s selves, and weren't suited to writing that music, so they all split up. There was no war, just a changing of the guard.
Grunge wasn't some rebellious movement that killed off hair metal. It was just the latest trend in popular music, just like the hair metal that preceded it, successfully pushed onto a new generation of kids via MTV.