A piece of music inspires expectations in listeners with its very first notes. And bad music does nothing but gratify every one of those expectations. Listeners can predict from the first few notes what the notes that follow will be, and so on until the piece is over. There is some comfort in that predictability, and it accounts for much of what passes for popular music.
Good music, on the other hand, frustrates the listeners' expectations. But it makes them think about what they were expecting and why they expected it. It surprises listeners with each succeeding note and takes them in directions they have never expected to go. Most listeners find this lack of predictability in good music disturbing, which accounts for its unpopularity.
But even acquired tastes in music can be rigidly conservative. When I was in college, and routinely burning the midnight oil, I would listen to a Denver classical radio station, KVOD FM, which had a late night request line. I would look into my dog-eared Schwann catalog and request music that the station rarely, if ever, played, by the likes of Bartok, Mompou, or Panufnik. I was fed up with the same old Mozart, Brahms, and Tchaikovsky that they played every day.
Most of the time, the station would play my requests, no matter how arcane some of them were. But sometimes they would not. On one particular night, I was awake until dawn and never heard the piece I requested. So I phoned the radio station to find out why. The person I spoke to put me on hold, which is always a bad sign, and someone else got on the line. She explained to me apologetically that if my request had been played, other listeners would call to complain. I was stunned.
It showed me that even someone sophisticated enough to appreciate a Brahms symphony would refuse to listen to a Bartók concerto or a Webern sonata - because it didn't sound familiar, it didn't sound like it belonged to the same tradition (even though it did), or to any tradition he could identify, it wasn't culturally pre-digested, it wasn't safe. If I had called and complained whenever the station played Tchaikovsky (not because he was modern but because he was a rotten composer), they would likely have considered me crazy.