I MUST agree that when talking or thinking about message, "coherence", deepnees, moving power, meaningful and challenging listen, NOTHING comes short of classical music.
Lacking - also in Italian, my mother language - the skill and knowledge to define "classical" music, I would try to suggest a naif, general definition: it's "classical" music, any written or coded in form, praxis and meaning/function music.
Amir quoted his beloved Persian classical music: oud or santur solo or traditional classical Persian music ensemble sure has a centuries old background and heritage on same par than Classical Indian music, with its raga system, where surbahar, sitar, tabla, dilruba and mrdigham owns VERY same (and more...) historic and social meaningful "weight" than our Western violin, piano, cello or any orchestral music.
Most of the time, the above mentioned music is several centuries old in instrumental techniques and music theory: and not only like for Anglo-Saxon vs. European countries and their Do-re-mi-fa-sol-la-si/C-D-F-E-G-A-B (formal) difference.
A broad, universal knowledge of Music around the World sure helps to correct errors, misunderstanding, intellectual closing, a priori... like Colin McPhee with his Tabuh-Tabuhan or Lou Harrison with his several compositions, both fell in love with Gamelan music from Indonesia; or Previn with his Sitar Concert dedicated to Pandit Ravi Shankar, I - underline this to be true for myself - prefere considering as classic any definitely peculiar, definite to a people or geographic area, played with acoustic instruments played, recorded or performed in natural acoustic environments.
It's globalization and not something new, BUT a never ending process, without boundaries or limits BUT interest.
Sure Bruckner, Mahler, Brahms and Beethoven, as highlights of (Western) classical music aren't more or less appropriate, rich and beautiful than "classical" Indian vocal music of, say, Pandit Pran Nath and his singing or - for classical Persian music - of, say, Djalal Akhbari and his santur playing... no hypes, here, and my sincere opinion.
... not considering them, here and now...
"Use your ears as your eyes" - Gertrude Stein
I was re-reading with interest a post by Roman with interesting and stimulating posts by Amir...