Through Mark Baker’s SimpleDB did screw up I just found a new rationalization for the un-RESTful nature of Amazon’s SimpleDB API by David Peterson at xml.com. For those curious, I have offered a RESTful version here.
David Peterson’s rationalization is simple. Since RFC 2616 recommends (a SHOULD) pipelining for idempotent requests, and since Amazon’s SimpleDB is "designed from a ground up to support highly parallel applications", SimpleDB ended up being what it is.
Simply hilarious. I hope that it it his interpretation, and not Amazon’s.