UPDATE:
Three thoughts came to me last night. First, how certain passages or phrases of the piece remind me of film music. As scary as Schoenberg can be, some of his stuff can be very cinematic. (I think Mark Swed has written how bits of serialism have shown up in movies, especially, if memory serves, horror movies.)
I usually groan when any event is opened up to audience questions. But the brief post-concert Q+A here was really illuminating, including the part where each musician spoke about his or her instrument, some of which were quite old. (As the owner of several guitars I could share their pride even though my instruments are not Venice-made or 19th-century.)
Finally: Composers like Schoenberg — and this starts with Wagner and Liszt, I suspect — felt the need to move beyond traditional major and minor keys, since tonality was supposedly confining. The musical innovations of the 20th century were supposed to allow you to do more. But listen to Transfigured Night, especially the way it was played the other night, with its moments of terror, guilt, uncertainty, pastoral, romantic sublime, and open-hearted forgiveness. It covers an enormous amount of emotional terrain.
When we listen to much contemporary music — including all but a few pieces from Schoenberg’s Second Vienna School — the emotional palette is vastly narrower. You can do more technically, perhaps, and it gets alienation real well, when you “liberate” all twelve tones in the octave. But with the musical language that came after this early piece, you can say far less about human experience.