Basically, read Zen and the Art of Motorcycle Maintenance. You'll only have to go through the first ten chapters to probably get an idea of why I suggested that. To elucidate for people who don't get it, and who haven't read it, One of the many ideas put forward in Zen... is that people can appear to be superficially similiar in their tastes or outlooks and yet have deep differences of outlook so absolutely fundamental that you may not even notice them. Its a matter of aesthetic worldviews. The dominant worldview at its most basic favours art which comments directly and unequivocally upon real life: at the end of the day, there's not such a huge aesthetic gap between, say, Big Brother and Broken Social Scene. This worldview values the subtlety of every day emotions and feelings, realistic stories and vignettes, internal references to a shared popular culture, and so on and so forth. This, at the end of the day, is in my opinion, a lot more important in peoples musical tastes than audial style. Audially, there isn't a million miles between Nick Cave and Current 93. Hell, they've made albums together. But, people have much more liking for Nick Cave because his songs, his most popular ones especially, tend to embody more realistic or recognisable stories, whilst Dave Tibet, whilst he does tell very personal stories, likes to the tell them in a manner that makes detailed references to the works of Aleister Crowley and the fates of his pet cats. This might be a bad example, but hey. Metal, of course, does not really embody this aesthetic. In fact, it embodies a completely opposite aesthetic. Metal is fantastic. Literally. It is about larger than life characters in unreal situations, dressed like Satans take on the village people. When metal comments on the world, it comments on issues outside most peoples experience, mostly historical and military. It is exaggerated, stark, brash, and comes off to supporters of the first aesthetic as adolescent and crude, whilst to its fans it can offer literally transcendent emotion. You will also find goth rock, industrial/post-industrial, fantasy music etc. in this aesthetic camp. If you look at what artists and songs in the metal genre are liked by indie fans, you can see how this comes off: a lot of people who are generally indie fans like metal ironically, ie, they view the whole thing as, basically, a post-modernist reference to itself. That's why when more hipster type people start a metal band it will do well in the indie community but completely tank in the metalhead arena: very few metalheads listen to Goblin Cock. They can smell the insincerity a mile off. Jazz, generally, belongs to the first aesthetic category, as do a lot of the people on these forums and indeed a general majority of the populace. To put it shortly: metal isn't cool.
Also, in considering the issue of jazz vs metal, it might be worth noting that, in America in particular, some elements have trickled down to the modern indie milieu of the rampant anti-racist sentiments of the cooler sections of the 60's counterculture. That is, there is an unconscious racial judgement made that sees metal as something inherently white, and thus crass, and jazz as something inherently black, and thus cool. Although, I say that its unconscious, but if hipsters want to mock metal, then the phrases 'white trash' and 'white supremacy', even if used purely as a joke, are not far behind. It is often subconsciously, or consciously, assumed that every metalhead who hates rap is probably just a little bit racist. Actually, due to his aesthetic worldview, most rap is pretty much the diametric opposite of what it is he wants to hear. He can't understand it on the most basic level. A lot of metalheads do probably have some subconscious racism, because a lot of them are white and middle class, but, in general, I don't think race really has anything to do with a bands musical output whatsoever, and, in some way, a lot of people do. I don't understand the hip-hop cultures seeming monomaniac obsession with race any more than I understand heterosexual men not wanting it up the poopchute. I mean, to illustrate an example: outside the NSBM and NSBM friendly twats, I don't think any metalhead would actually judge a band on, whether they were, say, black (like most of the admittedly ironically named Znowhite) or asian (countless amazing Japanese and other bands), they would judge them on the music, whilst, seemingly, a white rapper already has quite a hurdle to overcome anyway, and basically has to key in to black culture to have any success (whilst, a band, like, say, Sigh, might be entirely rooted in Japanese culture). I'm rambling off on this without being PC, by the way, so no offence to anyone. It's just, like I say, I don't ever actually consider race as an issue in music (or any walk of life, really), so I don't talk or think about this sort of thing much.
That's what I think anyway. I have sort of been considering writing an article on my blog on this sparked off by going off and browsing that Electrical Audio forum and basically not being able to comprehend the value judgements of pretty much everyone there.