Because music from the 90s was actually about making music and putting out quality songs. Now everyone sees the money to be made in music (not just artists, but producers, djs, songwriters etc) and everyone goes mainstream to sell more, no matter how shi**y the music actually is. They dumb the songs down so more people understand it, meaning more people listen to more of that music, and end up buying more. It's allll about the money for 85% of the entire music industry these days. It's sad
I think one of the reasons is that it was a "new area" It had a different sound than what everyone was used to, and the content was about new and different subjects and story lines. In the 90's, all types of music seemed to change, from rock to grunge to country. Everything seemed fresh.
I think the 90s bought out the real talent in bands and they showed the 90s generation what real music sounds like and we loved it. The best music people our age could possibly listen to formed in those years.
Because artists had real talent :o unlike many of the artists nowadays who need auto-tune or some generic song-writer to write their songs for them.