Setting up a new system would not be without hurdles, of course, however if the initiative is properly funded and is pushed from the cabinet-level (i.e. US DOE) down and the use of the new system is tied to federal funding for universities, then it will gain traction and prestige.
It might take a generation for the old guard to fall away but eventually we'd have a better, more transparent, fairer system.
Conspiracy theory aside, you have to realize that no law ever gets passed, or even makes it to a full vote, unless multiple parties are successfully convinced that they, their constituents, and their campaign contributors will benefit from the proposed bill.
No muddying of the waters intended. And you're right, I don't know exactly what the real motivations behind this are - however I am sure that there is more than simply the profit margins of publishers at stake here.
2 -- Actually, the publishers do have a lot of power. The universities are stuck in a bad equilibrium (in the game theory sense) -- if any of them individually deviates (by not subscribing to popular/restrictive journals and not publishing in them), that university is going to be the one to get hurt.
The only way out for universities is if they all cooperate and decide to ditch the restrictive journals. There are movements toward this right now (against Elsevier, for instance), but it's very difficult to gain traction. You can't just pick up the red phone to every university president and say, "hey guys, stop publishing in these journals, I set up a whole different process over here!" The journals have the prestige, so they have the power for now.
Response to #2: Good points. But don't forget that the government has the "Power of the Purse". If they tie funding to open access to papers, then some amazing things will start to happen.
http://www.hhmi.org/news/elife20111107.html
It would probably be considered dubious/anti-competitive if NIH and NSF launched their own journals, but because of the Open Access Initiative (which RWA attempts to reverse), NIH is able to host articles that have already been released to the public via PubMed Central.
The universities and government are looking to ditch the journals, and the journals know it. But it's a slow process.