The stuff reminds me of Frank Zappa. I like most of Frank's work, especially the do wap type of music that is popular. His other pieces follow Mr Carter and Edgard Varèse.
If you read a bio on Zappa, you'll know Varese was a sort of hero of his from a young age. The thing is, these composers aren't at all alike. Zappa I think never did twelve tone. I think neither did Varese. Of course Zappa was born the last of them by a couple/few decades, too, so he didn't do anything original in the way of harmony. He's just well-known in pop circles because a lot of what he did was during the 60s, and especially as he played guitar and he had a 'rock' band, people got confused and thought he was in the same category but doing really 'out there' stuff.
Of course, his preferences weren't that similar to other avant-garde composers (of which were decades his senior anyways) and given these as well as his young age, he certainly wasn't well-thought of in 'classical' circles. However, all his stuff was scored and he had full capacity to compose more conventional material. I haven't cared for anything of his I've heard, but I do recognize his ability and all.
It's the off the wall sounds that would be good in a psycho thriller movie, but I cannot say I could sit down and listen to that mish mash and get anything out of it. I would have to take some sleeping pills to get through the entire piece.
Ahem. All those movies, tv, etc stole...I mean appropriated such techniques, often decades after they'd been developed in real music.
If you were into recreational drugs, I'm sure that would give the experience an extra twist, as I'm sure the guy had an audience in the 60s and 70s. It definitely sounds like that guy was on something when he composed it. The Harvard remarks says it all in the interview.
I don't think so. He was after the Laudanum, opium, and cocaine elite eras. Which remark are you referring to?
A nonconformist will always have a market to tap into. Specialist music is definitely not a bad thing, and when listeners (myself included) tastes develop, I'm sure Elliott will have a few more admirers.
It's not specialist music. It is, as he says, music for musicians - which does also include those who are mentally inclined to listen to it.
Did you notice the many empty seats in the second video? 
It was a student performance at a university. Not that the music is widely appreciated, but that was a fairly large hall and had a relatively large attendance, even so. Plus it was during the day I think. For some reason they leave the house lights on during day concerts.