I think the main attraction of object storage like S3 is that it already solves the hard problems (distributed-ness, scalability, durability, etc) with a simple

I think the main attraction of object storage like S3 is that it already solves the hard problems (distributed-ness, scalability, durability, etc) with a simple(r) API. Also, apis like S3 are defacto standard with many vendors supporting a descent subset of it.