Sorry I did not see this post until now. Great modern music is still being made and much of it is ascetic and atonal. Much of it, and just like all music 90%, is not very good, but that 10%....!
Technically playing modern classical is extremely demanding on both the listener and the players. For most people these days classical music is an acquired taste and modern classical music is even more of an acquired taste for both the players and the listner. But in the end it is highly subjective whether the ends justifies the means. I happened to believe it is well worth the effort. And most players do too, at least the ones I have talked with. Because in these cases, the composer and the musicians can talk about the performance together, and actually change things around if need be. It was quite informative talking with Gidon Kremer after his performance of Schnitke's 2nd Violin Sonata, and how the two made a few changes that would enhance the performance and enhance the piece aestetically. He showed me his score, with all the changes marked that the two had made. You cannot say that about a Beethoven or Schubert piece at all. Beethoven who was a great pianist never played his sonatas the same way twice, he did not follow his own markings! OK so who is say which way is correct, good question.
My moniker says I love Schubert, and I do! But I would rank some of the moderns as my favorites too, but after Schubert, Beethoven and Brahms, I would go see a Schnitke, Gorecki, Bartok or Penderecki piece before I would see something like Mozart or Bruckner. These guys are inventive, imaginative and just plain aestetically involving.
BTW, what radio station plays Modern classical music, I would love to know that one!!!