Beethoven a Hooligan!

Did he ruin classical music? Did he turn it from a vigorous, playful, outer-directed form into a wallow of megalomania and bloodlust? Was he Anakin Skywalker to Mozart's Captain Kirk? (Mozart, after all, had happy and frequent sexual adventures, while I think Beethoven was all tortured n' shit with the unrequited love. Maybe I should look that up. What I know about Beethoven consists of three minutes of watching Gary Oldman in period costume stalk around angrily on TV while a voice-over rants about not wanting his Many Enemies to discover that he's deaf.)

The interesting thing is that you can see similar trajectories happening in American popular music too, both overall, AND within the careers of individual bands. It seems like everything always starts out happy and clear, then goes all Beethoven. Star Wars (admittedly NOT a piece of music) started out as an adventure and ended as a claustrophobic tragedy. American popular music started out cheerful, playful, hedonistic, winking ("Beat Me, Daddy, Eight To The Bar"), and then rock n' roll kind of jolted everyone, but *it* turned out to be cheerful, playful, hedonistic and winking too compared to what came next (I give you Black Sabbath and Led Zeppelin). And then you've got the Beatles, who started out (yep) cheerful, playful, hedonistic and winking, and ended up all "Happiness is a Warm Gun."

Are there any examples of the reverse? Careers or genres that started out angsty and then lightened up?