The ideals of Western art music are unique to music history, where most music is closer to folk forms and is less concerned with High Art than with all the things folk musics concern themselves with--community, religion, love, etc. That's a maybe inelegant way to say something a book could probably be written about. But I think one reason a music "dies" a slow death, like classical and jazz, is that they become institutionalized. "Classical" is institutionalized by definition--it must be made by highly trained specialists--and Jazz has gone that way, as well.