From the Vox article:
"If you pretend like there’s no other music out there, that Beethoven is the greatest music that ever will matter,” says McGill, then orchestras will alienate new listeners, since “we’re not promoting any of the composers alive today that are trying to become the Beethovens of their day.”
I agree. I have always been in favor of listening to New Music. It also seems that New Music can be attractive to young listeners. In late 2004 there was a concert at the Boston Symphony featuring Elliott Carter's modernist Symphonia, and Beethoven's Eroica symphony. A person in our group spoke with one young listener who expressed a clear preference for the modern work. A young lady (about 25 years old), who once sat next to me during last year's Stockhausen festival of his opera cycle Licht (Light), said with the deep enthusiasm after one extreme avantgarde electronic piece, which I thought would be really an acquired taste, that all the music that she had heard during the festival was "a miracle".
Of course, these are just anecdotes. However, I can also confidently report that the most attentive, least coughing, least noise interrupting audiences that I have experienced consistently were in concerts of modern classical avantgarde music.
Nothing against Beethoven -- I love to regularly return to his music, recently with his Choral Fantasy -- but there is other music out there too.
Certainly, the modern large orchestra is by nature, by its makeup of players, slanted towards the 19th century repertoire.
I wish I would not just hear more modern music in the concert hall, but also more other older music like Haydn, for example. What a genius composer who deserves to be much more widely played and heard.