So How Much Are We Indebted To The 20th Century?

From a forum topic at NetNewMusic:

Let's see what they did for us...

1. They destroyed the classical music audience, scaring them away from concert life.
2. They created animosity between performers and us, depriving us of the natural interest performers have in the music of their time.
3. They entrenched themselves into academia, creating a network which now controls, throughout the world, access to performance resources, grants, etc.
4. They created a progressivist attitude which seemingly labels any type of music which comes after them as anti-progressivist, naive, and sentimental.

I'm sure I'm leaving out a few of their great contributions to the world of composing.