Bands the world can do without:
-Boy bands.
-Girl groups.
-Boy-gril bands.
-Any band where they lip sync on stage and don't play their own instruments and/or write their own music
-Any current band that is egotistical enough to think that they are original and don't respect their influences.
-Metallica from 1992 onwards
-any band that relies more on image and marketing than the actual music they play (which generally applies to all of the above)
Nirvana was nothing more than average, and doesn't deserve the kind of recognition they have received. If they found an old recording of Kurt Cobain farting, radio stations would fall over themselves to see who could play it the most. Yes, they did have an influence on music...they took the personality and fun out of it and made it boring. And Kurt introduced the world to Courtney Love...if I was married to that talentless whore, I'd have shot myself, too.
As for 80's hair bands, I miss them. Sure they mostly played shitty music, but the music was better than most of the shit being played to day, and they were brainless fun. For that reason, I also appreciate some of the current "punk" acts out there like Offspring and Green Day. Sure, they're not incredibly talented as musicians, and their music is formulaic, but at least they play their own instruments and have a sense of humor.