I don't really understand insulting particular bands - and yes I'd agree it's insulting the fans and almost trying to put them off liking the music they do.
I don't like Abba for example but I wouldn't dream of insulting the music - I can understand why people do like them, and they do (I understand) have complex musical progressions.
It's almost like the insulter isn't sure about liking the music they themselves like, and have to try to put other people off the music they like.
oh come on there are loads of bands that deserve a slagging off. worth slagging off, quite rightly.