Also, it's a sort-of-layer because it really is dependent on details of HTTP (such as the existence of headers) to operate so it is not an independent layer. In networking I'm much happier when layers are independently specified.
Also, I think the implementation of header compression is poor because it uses a fixed dictionary that is based on current HTTP headers. There's no provision for negotiation of this going forward. It would be better if the compression dictionary were negotiated on session creation. Notice how the dictionary has been updated between standard drafts. Once it's in the standard updates will not be possible.
And SPDY requires TLS which means that if it were HTTP 2.0 it would require the deployment of certificates everywhere. That's an added expense for a web site operator. Unless SSL certificates are suddenly free and trivial to deploy then that would make HTTP 2.0 complex.
I would much rather see a proposal to change HTTP so that pipelining works, using textual headers and not require TLS.