Sometimes history moves slowly. During his life, Bach was best known as an organist; sure, later composers studied and loved his work, but it wasn't until the mid 19th century that he started to get the reputation that he has now.
I think komponisto is implying that there was plenty of popular music back then as well, but most of those composers/performers didn't enter the canon.
However, I think there's another factor at play here - "art music" experienced the same academization and post-modernization that we saw in the visual arts. Serialism, musicque concrete, aleatory composition - all these things pushed the boundaries of what "music" actually meant, going against popular sensibilities in ways that (and I could be wrong here) the "art music" of previous centuries did not. The idea of linear stylistic progression totally breaks down once you get to the mid 20th century, so if you want to construct a convenient narrative, you've got to grab onto popular music or jazz.
I think the Second Viennese School tends to get singled out, because they are the major overlap between "music that some devotees of 'art music' really enjoy" and "music that some devotees of 'art music' think is too bizarre." If you go earlier, Mahler has too many fans, and later, people like Xenakis don't have enough.
However, I think there's another factor at play here - "art music" experienced the same academization and post-modernization that we saw in the visual arts. Serialism, musicque concrete, aleatory composition - all these things pushed the boundaries of what "music" actually meant, going against popular sensibilities in ways that (and I could be wrong here) the "art music" of previous centuries did not
It's true that in the 20th century, art music became advanced beyond the point of being immediately accessible to most non-spe...
Followup to Stuck in the middle with Bruce:
Bruce is a description of masochistic personality disorder. Bruce's dysfunctional behavior may or may not be related to sexual masochism [safe for work], which is demonized by most people in America. Yet there are ordinary, socially-accepted behaviors that seem partly masochistic to me:
Question 1: Can you list more?
Question 2: Doubtless some of the behaviors I listed have completely different explanations, some of which might not involve masochism at all. Which do you think involve enjoying pain? Can you cluster them by causal mechanism?
Question 3: When we find ourselves acting masochistically, should we try to "correct" it? Or is it part of a healthy human's nature? If so, what's the evolutionary-psych explanation? (I was surprised not to find any evo-psych explanations for masochism on the web; or even any general theory of masochism that tried to unite two different behaviors. All I found were the ideas that sexual masochism is caused by bad childhood models of love, and that masochistic personality is caused by other, unspecified bad experiences. No suggestion that masochism is part of our normal pleasure mechanism.)
Some hypotheses:
My guess is that, if it's a side-effect (e.g., 3) or a non-causal association (4), it's okay to eliminate masochism. Otherwise, that could be risky.
These all lead up to Question 4, which is a fun-theory question: Would purging ourselves of masochism make life less fun?
ADDED: Question 5: Can we train ourselves not to be Bruce without damaging our enjoyment of these other things?