A) Independant music is no more genuine than music on a major label. not all Major label artists are Britney Spears. There are plenty of perfectly talented and genuine artists that are on majors, and they have just as much to offer to the scene.
B) Marketing and distribution are a double-edged sword. There are many albums I spend months to years looking for in vain because indie labels tend to have limited distribution and limited pressings. While some indie releases are rereleased, many you have to find used (which is a very hit-or-miss operation) or you need to shell out $50 on ebay for the album. Or downloading, which isn't an option for those of us without broadband. You can claim that this makes a band "sellouts" but if the band really cares about their music, they'll negotiate for full creative control (look at, for example, the Mars Volta, who produced their sophomore LP themselves without any say from Universal), and plenty of indie labels still have other people produce a band's music for them. There are plenty of bands on major labels with more creative control than bands on indie labels. As for marketing, mostly it's to say "hey, this band has a new album out." No one's saying "oh dude, listening to the new Foo Fighters album is going to make you 10 times more attractive." I only wish that I could be informed about upcoming albums by various independant bands that I enjoy, often that information is buried deep in the news posts of a very spartan website (apparently, for example, Pretty Girls Make Graves are recording a new album, but you wouldn't know this unless you really looked for it). Honestly, I wish that many of my favorite independant bands were on bigger labels; they'd tour more, play more all-ages (not a big deal for me, as I'm an adult, but more an issue for other folks), and their albums would be more accessible. Music should be about the music, and good stuff shouldn't be so damned hard to get ahold of. Good music is not good because it is esoteric, it is good because it is good.
As for genres, I don't have broadband. I don't have other free unlimited access to music. So I sometimes have to shell out $10+ for an album on faith. I would rather spend that knowing that they play a style of music that I tend to enjoy rather than just being told "oh, they're good." There are plenty of bands other people have told me are awesome that I think are talentless trash (Interpol, for example), or are decent, but I want to break the CD because it's boring as shit (Sigor Ros comes to mind). If the band focuses on the technical aspects that I find inspiring and plays a style I enjoy listening to, even if it's subpar, I'll probably get a lot of pleasure out of the CD, guilty pleasure, certainly, but pleasure nonetheless. But if they focus on things I find completely banal and play a style I find completely lame, I will probably not listen to that CD and I will have wasted a bunch of money. Are you beginning to get my point here?
Anyone's going to go into music with certain tastes. There are things I enjoy in music. There are things that I find obnoxious. There are things that I get distracted by and things that I find absolutely inspiring, be it specific instrumentals, style, or lyrics (and by inspiring, I mean that I'm in a band and it opens up new ideas for composition and such for me). There are other forms of music that just do nothing for me. No matter how much I listen to Postal Service, I'm still going to hate it, and I'm going to get nothing out of it. This isn't because I'm narrowing my tastes based on genre, but because I fucking hate that style of music, it makes me want to kick the shit out of someone, and I find it totally bland. So once again, why should I listen to something just like Postal Service if I hate that shit? And why shouldn't I listen to something like BearvsShark if that leaves me feeling happy and excited and I can't wait to get back to my bass because I've seen someone do something new with a style I like a lot, and that makes me want to try new stuff?