Frogman I knew you could explain this much better than me.
****Why were all the East Coast guys black and all the West Coast guys white?****
"West Coast guys white"; that even went for the music, the Black guys even sounded White; I thought Buddy Collette was White for the longest. His good friend Mingus, even said his music sounded White.
When I was in LA, I talked to musicians who could have been famous if they left LA, but since they could make a good living there, why leave?
West Coast jazz reflected the lifestyle there; laid back and cool, always casual.
I have nothing to add or subtract from your post, it was complete.