[quote]I have said this over and over again: does anyone think that if "American Idol" was around 40 years ago that Mitchell or Leonard Cohen would have made it?
This is such a bullshit comparison. Leonard Cohen wouldn't have made it on American Bandstand or Hullabaloo, either. When did he ever even get played on Top 40 radio? Joni had a hit with "Big Yellow Taxi," but that's not exactly to her credit; a lot of people my age (30, btw) know that one song, think it's trite and silly, and don't look any further.
Who takes American Idol winners seriously, as actual entertainers rather than as contestants in a singing version of Survivor? People who would have bought that shitty, shitty commercial pop music that did so well in the '70s, that's who. People who bought Doobie Brothers albums and made "You Light Up My Life" a hit.
The musicians you're looking for don't get played on the radio because: 1) radio is a pay-for-play business now; 2) Clear Channel is a soulless corporate monster; and 3) for decades now, record companies have been going for the quick buck, putting no money into development, squeezing whatever they can out of new artists and tossing them out after their first dud album. Bands who make the mistake of signing with major labels almost always lose money. See Steve Albini's early-'90s essay "The Problem With Music." Thomas Frank's book The Conquest of Cool, about corporate co-opting of genuine emergent trends, is also a good read in the "what's the matter with kids today" vein.
We don't have a monoculture anymore. Blame cable. Blame the re-segregation of radio stations that came with the FM band. There's a lot of interesting work being done in different genres (few of which involve guitars; I mean, if you were a young person today, wouldn't you want to make something new?), but you have to look for that stuff yourself. The thing is that thanks to the internet, it isn't actually that hard.
You have to look back a lot further than 1990 to find things going wrong with radio. Good guitar-based music and guitar-based music that made it on the radio started diverging sometime in the early '70s. You ask whether the Beatles could make it today; I ask you, why couldn't Big Star make it in 1972? How come Nilsson and Randy Newman only had novelty hits? Why didn't Roxy Music make it over here? What went wrong for Nick Drake and Sandy Denny and Arthur Lee and David Ackles and the Velvet Underground? Besides, if the Beatles, cutting-edge as they were, were around today, I find it hard to believe that they'd be a rock band.
I'm guessing that you missed out on the decades of vital and interesting and also commercially successful hip hop we just had. Wu-Tang? Outkast? Black Star? What about the exciting, futuristic pop music Missy Elliott and Timbaland were making back in 2001, before Tim gave up ecstasy? Going back futher: Eric B and Rakim? Public Enemy? I get that you don't like dumb lyrics, but blaming Dr. Dre (successful because he's such a great producer; you know that everybody knows he's not much of a rapper, right?) for not being Joni Mitchell is like blaming Rick James for not being Graham Parker or something.