Kurt never changed anything. Kurt took what was starting out, and made it simple for the common folk. He wasn't the greatest writer, or song writer ever, or even qat that the time Nirvana was big. All he ever did was write some simple 3 notes, and it became a smash. He had no diveristy in his song-writing, his singing or his guitar playing. All he wanted is attention, got it, and couldn't handle it, and basically blasted his brains away.
I'll agree with Cobain, Joplin, Morrison, but to lump Hendrix with those three is absurd. He was going to be a legend if he was still alive today as we speak. While granted he wasn't the best guitarist ever, or even at the time, his style of guitar soloing, has influenced so many people on the guitar through out the years
Well, Kurt's the one that broke it down. Yeah, Soundgarden and Green River and Mudhoney basically started the sound of grunge, but Nirvana expanded on it and made it accessible to the mainstream with Nevermind. And then after that, it simply exploded.