Like many people of my generation, I grew up around pessimists. It seems to me that my generation was simply filled with Eeyore parents (other people's parents seemed almost as pessimistic as mine seemed to be). There was so much wrong with everything in the larger world: drugs, hippies, racism, crime, communism, the Iron Curtain, Middle-Eastern terrorism (particularly the Iranian hostage crisis), the energy crisis, antisemitism, political corruption (particularly Watergate), and pollution.
While I was growing up I was very much aware of the phoniness that goes with "importance," so I never trusted people in power. I still don't, but now and then I make an exception. I have noticed (she mentions optimistically) that some of the people in power who have an idealistic world view (and are willing to work to make it real) tend to be a few years younger than I am.
I always thought that music could be a way to transcend all that was horrible in the world, and that if my musical intentions were "true," I could do something of value and, perhaps, make the world a better place, at least while the music was happening. (My family nickname when I was a child was "Pooh.")
I don't know if that kind of idealistic view of improving a corrupt world is practical (as in the Hirschmann sentence I quoted yesterday), but idealistic music making can make it possible for chunks of time to be pure and true. A few minutes of beauty and idealism can be more meaningful than a whole day of ugliness and doom.
Writing music is itself kind of like idealism in action: there is an ideal balance for a piece of music, there is a "right" organization of pitches and rhythms, and there is an ideal performance in a composer's inner ear. With a lot of skill and a certain amount of luck, it is possible for a composer to put together phrases of music that can saturate chunks of time with the feeling of idealism. With more luck, it might even be played by musicians (perhaps musicians the composer doesn't know personally) that share his or her idealism. And maybe it will allow a few minutes (or hours) sometime in the future a bit more idealistic for someone playing or hearing the music.