Actually, this is kind of the opposite of constraint breeding creativity. You have removed the constraint of having to make a piece of music playable by a human and now you might have a 20 million note song not because it sounds good but just for the novelty of having so many notes. Like any other medium for art, there will of course be good and bad pieces created. But a million old-school geocities web pages w/ autoplaying embedded MIDI tracks I think serve as a good example that the default judgement is going to be harsh.