You need to understand the context of when Nirvana came out before you start listening. At the time (1991), 80's hair metal was still king. Men dressed like women - makeup, women's clothing, hairspray, the works - singing overly indulgent songs about drugs and sex. Not saying anything of any value, just one continuous party.
Rock music was this:
and then out of no where this dirty guy from Seattle dressed in jeans and flannels came and dropped this:
Everything changed. None of that old party shyt was cool anymore.
Rock got grimy again. It's like if a 2018 version of Mobb Deep dropped right now and everyone instantly realized how absolutely retarded music had gotten and stopped listening to all of the pop fake bullshyt and went back to timberlands and hoodies.
I pray that we have some shyt like that happen to get hip hop back to something with substance on a wide level.
On top of all the societal shyt the music is dope. Even for someone who doesn't listen to rock. The MTV unplugged album (you can watch it in YouTube) might be a good intro. Then try Nevermind.
Good analogy