Unfortunately, the manufacturers obviously don't see enough value in open source drivers to offset the risk of patent suits and/or cloning of their special hardware features. It's a matter of perspective - we see no legitimate reason why they should not release their internal documentation to interested/qualified open source developers, but they probably see themselves sunk if they did. After all, look what happened to the trailblazers in open source graphics docs: 3Dfx, Matrox, 3DLabs, etc.
The only solution for people who value open source drivers is to stop buying their products and develop our own to compete with them. Relentless lobbying will only waste their time and make them less likely to deal with folks in the open source community.
For people who don't care about open source drivers as long as a binary driver works good enough for you, just go ahead and buy a card from the leading manufacturers. But don't blame Linux when the driver blows up or acts strangely. As long as these vendors refuse to cooperate with the open source development model, the onus is on them to go the extra mile and produce a stable product that interoperates with the open source world.
So far, they haven't done well at that challenge, suggesting that either open source developers are deliberately foiling them (some people believe the absence of a driver abstraction layer falls along these lines), they employ incompetent programmers, or they are simply not providing their best effort as a company towards Linux support. I suspect the latter, and only market share will change that. (Hence the driving force behind platform advocacy, as opposed to the 'zealot' label that platform advocates receive from neophytes who misunderstand or reject the fundamental correlation between platform market share and quality of vendor support)