i remember coming up with a composition idea in college which my composition professor rejected.
the concept was to define rhythmic motives and song structure and leave most note choices to the performers.
(from pitch class sets, chord changes, etc...)
he said i was "just trying to get out of the work"
later he wound up using the idea in one of his compositions...
interestingly, i have known some very good performers that were quite nervous about doing improv,
but were ok with "aleatoric" music...