I think it would be better to say that it's random-inspired - you get a riff or a piece of a melody, but the whole song still has some artist-imposed structure

I think it would be better to say that it's random-inspired - you get a riff or a piece of a melody, but the whole song still has some artist-imposed structure or else it would be unlistenable. There's some nuance that I feel is worth distinguishing with its own word.