If you disagree with this principle, then you disagree with the most fundamental activity that has resulted in Linux having any measure of success in any market. If you want to try and mount a counterargument, go mount Steve Ballmer's ass instead -- you'll be more successful that way. It's VERY hard to argue with success, and success is the product of the positive feedback loop of open source. It only falls apart when people only use and do not give back any contributions. The higher the ratio of companies that don't contribute vs. the companies that do, the worse off the open source ecosystem is going to be, which eventually means that anyone who's using open source -- whether they're contributing OR NOT -- is ultimately going to lose out, because the positive feedback loop will turn into a negative feedback loop due to a lack of contributors, which will further fuel adoption away from the libraries and common code as they bitrot, and so on and so forth until a large number of projects are effectively "extinct" (no developer activity and no users). It's a reasonable comparison to a food chain in nature -- is it that hard to understand?
And BTW, before you accuse me of being a hypocrite, http://launchpad.net/rbpitch is my work, along with several other projects and patch contributions to PulseAudio, ALSA, Rhythmbox, Gnash, OpenSimulator, and Vala.
You might say, "well, Unigine never has to contribute to drivers on other platforms!" -- No shit, sherlock. Linux is different. It's developed different. It's used different. The ecosystem is different. The way that it sustains itself is different. It should come as absolutely no surprise that there is also value -- monetary value for Unigine -- to be had in activities such as contributing to the open source drivers, to make them better, to make their games run better, to attract more sales and more third-party developer licenses. You can't apply the norms and values of the proprietary operating system world to an open platform, because those norms and values are invalid assumptions when the principles on which the platform is based are different.
If you're wondering what those principles are, you might want to start by reading literature such as the Open Source Initiative's "Open Source Definition" at http://www.opensource.org/docs/osd or Richard Stallman's book, "Free Software, Free Society". And before you accuse me of being a Stallmanite, realize that I'm an equal opportunity idealist: I love the OSI's ideals as much as I love the FSF's. They both lead generally toward the same goal, and they both oppose naive, 20th century, proprietary-thinkers. One may be a little more practical than the other, but I'll take the positive qualities of both camps in unison and make the best of it.
A company that responds to its customers -- gee, what a concept! I hope you never enter the game development market, because your ideology is exactly the mentality that has kept Linux out of the gaming market since the inception of the free desktop. Unigine, on the other hand, genuinely seems to care about changing that problem for the better, and it would only be logical for them to contribute a little more by working on the open drivers.
And who the hell are you to say what Unigine wants or doesn't want, or intends and doesn't intend? They may not have initially intended to support the open drivers, but clearly that attitude has changed, regardless of the past. Whether or not their support for the open drivers is "grudging" (attitudes like "grumble grumble, damnit I don't want to support these stupid broken drivers.... OK here's a patch that helps them, now go screw off"), the fact is that they're helping make their engine work better with the open drivers. Why do you oppose this? Are you a Microsoft shill?