Thing is, most people who criticize others for their taste in music don't realize that not everyone puts so much importance on music.
For instance : a chick listening to Justin Timberlake/Britney Spears/etc... does so because it makes her move, it makes her dance, etc...I can't criticize her for not listening to Led Zeppelin, for example, that would be stupid. She doesn't look for instrumental or lyrical prowess, she wants something to play in the background while she puts her make up on on her way to the club. Same thing for Nelly/Ludacris/etc...fans.
Linkin Park, Limp Bizkit fans, these guys mostly want music to headbang to, to get angry to, etc...They like the genre for what the genre offers, so it's pointless for us to tell them to listen to something else. If they get off on screams and power riffs, what would they gain from Sigur Ros, Nick Drake, Johnny Cash, or Gary Jules? It's silly. It brings them nothing, so why would they make the switch?
The reason many get pissed about it is because they think everyone takes music as seriously as they do. But bottom line, most people listening to commercial pop want something to dance to. They don't care about the rest. The obligatory ballad is just a bonus, that they force themselves to like. Boyband fans are head over heels in love with the members, they don't place any importance about the music, whatever they might say. Limp Bizkit and the like are generic, sure, but they are loud, angry, and most of all accessible to people who need something to give out a "pissed off" attitude. That's mostly what the hardcore fans are about. Etc...etc...Not everyone listens to music for the same reasons.
I bet most people hating on a band can find something they liked in it if they tried. I can appreciate anything. I seriously appreciate Justin Timberlake's "Cry me a river", for instance, as it reminds me a whole lot of Michael Jackson's style. I was also one of the first to like "In the end"'s hook by Linkin Park, even though I've never bought/downloaded a tune of theirs. It's stupid to dismiss anything. I give everything a listen -and I do mean
everything- and keep what I like. I've got nothing to lose, and only music to gain.
I can also appreciate a well put together bashing though.