I'm working on a distributed S3 cache that supports just two functions, pread style contents of a file and all the elements in a directory. I've worked on other systems that represents this entire structure as RDF triples, which leaves you with just query and insert. To come at it from another direction EFS only implements about 2/3 of NFSv4, and S3 was perfectly functional before they larded it up with all this policy stuff.

I'm not saying that there weren't reasons to add these functions to the protocol, but if your aim is minimalism, then you can do _much_ better, and I think there is a real benefit in having a bare bones protocol that anyone could implement in many contexts.