I'm not going to try and link this to what anyone else has been saying, but isn't the problem that music has become more important in terms of defining identity [however shallow and corporate that definition is] and subsequently music and its creation is no longer primarliy the domain of the disaffected, but rather nigh on everyone you'll ever meet. Fame and idolisation are more imporatant than content or genuine apreciation, maybe this has always been the way?
In the same way that the majority of the populace has little interest in the intcracies of, say, politics or war or enviromental issues, there is little demand for a musical representative of the fact not all is rosey. Bands like the ones already mentioned may say fuck all off interest to a rebelious mind but it blatently doesn't matter, by liking them their fans have a pre-built identity with a million other clones to validate their cool. At university it seemed the first question people would ask is "what music do you like?", after i while i gave up trying to justify my choices as it became as pointless as trying to explain why i didn't like watching telly.
I recieved a couple of CD's last week from a mate who's about to bring out his first releases, the first was upbeat hip-hop about girls/parties/drinking etc. which he was happy with. The second was introspective, dark and discontented [sample lines: "..flew from the word go with plenty of perno, vigilante reading Dante's Inferno, astrology philosophy, i delved into to prophecies, but all these colleges and ology's couldn't offer me, a way to live to so i patiently evaded it....] though he was v. worried that no one would like this one.
Surely the only way to combat piss weak music is to source things with soul or meaning and support those acts...