Also, because there is no such a thing as "SPDY" what you are referring to is "SPDY 2 as implemented by Google Chrome and almost fully documented by Google". SPDY is a work in progress. If you want a real deployment to be possible, you need to have at least a fully documented basic core that has been discussed openly, not just an implementation from a corporation subject to changes whenever internal pressures require it.
Now it is, before it was not. And that is exactly my point in my reply: you cannot take whatever you call "SPDY" at the moment (implementations + wiki pages) and call it "HTTP 2". You need to document it, propose it, discuss it openly, accept criticism, fixes and, if needed, radical changes. This is what is happening now in the HTTPbis working group and is a good thing, but it is not going to be a rubber-stamping process for SPDY as it is now, I hope.
That's probably why HTTP/2.0 is going to be based on SPDY, an attempt to codify an emerging standard.