I think you missed an important link here: opening the API is not the same as making a good standard. The latter tends to take years. The former... Well, Google internal APIs often have minor changes every couple weeks. And the standard of documentation is more or less "go read the code". Opening those would not be useful. I don't know if Facebook is any better. But their motto is "move fast and break things", so I'm skeptical.
don't forget that there will be competition on the protocols as well, I'm not just arguing for protocols as a means for more innovation on the client side, but also more competition on the backend itself. If data becomes portable, which is one side effect of protocols, competition on standards itself intensifies. So if Google and Facebook are bad stewards of their APIs, there is room for competition to emerge. Google does stuff that sucks on their end? Use existing APIs to migrate over to dropbox or whatever, tell your users. In an open market there is an incentive for good standards.
