I don't like the dichotomy classical-pop really, because there is so much music out there that doesn't fall into these categories: Jazz, Rock, Folk, Blues etc...not to mention a lot of music that defies classification. And lots of it is innovative and "classic" in the sense that it will most likely stand the test of time as long as some of the romantic era composers have.
We should also separate music as a listening experience and a creative experience. I think much of art music is kept alive because it is often more easily "usable", it was usually composed to be performed by different people instead of a one time creation, a combination of the music and the performer. You can buy scores and play it with one instrument at your home more easily, like solo piano music, instead of needing a lot of equipment or a band to recreate it. If you get good enough you can sound like any pro and this motivates you to practice and get into the art music scene, which is not difficult to find usually. I had an electric guitar as a kid, but found it a bit uninspiring not to be able to really play anything I wanted with it because I didn't have the drums and bass, not the mention the voice. In those days it was quite impossible to find others in my age group who wanted to put together a band for that type of music. If I consider vocal music, there's also less emphasis on the personal quality of the singer's individual voice. If you have the skill you can sing an aria convincingly and will hardly be compared to an original performer, since those were never recorded. But most of us won't sound like some famous rock singer no matter how much we rehearse, so we can sing the song but there's always the original recording in people's minds.