Why Mingus and Coltrane didn't Play together ?

There's Coltrane & Dolphy recordings.
There's Mingus & Dolphy recordings.

Your answer probably deals with Mingus. He was a very headstrong/opinionated Bandleader and composer.
I doubt he woulda allowed Trane to go on those 20-minute exploratory solos. You don't woodshed on the bandstand...that kinda stuff.
:)

Sometimes, these dream groups don't produce the 'best-ever' music, either.
 
There's Coltrane & Dolphy recordings.
There's Mingus & Dolphy recordings.

Your answer probably deals with Mingus. He was a very headstrong/opinionated Bandleader and composer.
I doubt he woulda allowed Trane to go on those 20-minute exploratory solos. You don't woodshed on the bandstand...that kinda stuff.
:)

Sometimes, these dream groups don't produce the 'best-ever' music, either.

Lots of big name players didn't want to work with Mingus. His temper wasn't worth it. That's why he had so many relatively unknown (but still very talented) players in his bands. Added benefit is that he could more easily ply them to match his vision.