I believe that one reason so many of us don't like much of the new rock is partly generational but I also believe it's also the type of rock that's being offered. I know a guy in his 30s, who came of age during the time the 2 big grunge bands, Nirvana and Pearl Jam, rose to the top. He didn't like either of them and preferred the classic stuff. I asked him why and he said that modern rock was too depressing. He called it "angry young man music" made by a bunch of alienated youths who really had nothing to be angry about. He understood that all rock had some of the same rebellion, alienation, and anger he spoke of, but he also said that song for song classic rock had more party records and positive vibes than any of the current stuff does. I think he was right on the mark. The Beatles, Beach Boys, Chicago, even artists with a political side to them had many upbeat moments.
Well, we know how Cobain ended up, so that wasn't an act. Eddie Vedder has always impressed me as someone who needs to be on psychotropic drugs or something.
In the case of Chicago, the two big singles from the V album were Dialogue - a very political (yet somewhat upbeat) tune and Saturday In The Park, a warm, sunny celebration tune, showing the versatility of that band at the time, so point well taken.