Seems like a pretty easy cost/benefit analysis to me:

I can either spend thousands of dollars worth of my time on updating the driver, or I can pay someone else thousands of dollars to do it. Or I can spend a fraction of that on a new video card.

Seems like the only solution for Vista users is the only solution I'd ever have gone with, anyway.

Sure the cost/benefit works out the same for you (which is why no one has done the work), but that's different from the full set of options available to you in both cases.

How expansive do we want to be about what the full set of options is, though?

I tend to fall on the side of the root poster - if having a stable driver API means Linux gets more commercial driver support, then that's the one that has the highest cost/benefit in my book.

In practical terms, being able to hack on open-source drivers isn't particularly useful to me, but having an easier user experience with Linux on the desktop (and, more generally, having Linux on the desktop be something more than an also-ran) would benefit me immensely.

I skipped Vista, however my XP drivers were fully supported on the upgrade to 7.

Some xp drivers work on 7, most don't. Also unlike user space, you cannot run 32 bit drivers on 64 bit windows, so unless you were running 32 bit win7 you needed 64 bit xp drivers, which were rare. Are you sure you explicitly installed xp drivers and didn't just happen to have hardware where windows shipped matching drivers or could download them from the windows driver database? (Or downloaded an installer bundle from the manufacturer's website that just contained drivers for all supported platforms..)