It seems to me that, in pretty much every field, the most rewarding tasks, often with the most highly regarded results, are the most constrained— rhyming scheme

It seems to me that, in pretty much every field, the most rewarding tasks, often with the most highly regarded results, are the most constrained— rhyming schemes and meter in poetry, immutability in programming, whatever. It could just be freedom from the anxiety of choice (and just admiration for the creator's ability to succeed despite these constraints on the part of the audience). I feel like there's more to it than that, though.