I'm an Open-Source advocate, don't get me wrong.
However, they are under no obligation whatsoever, so why should they? What advantage do they get from opening them? What's going to be the thing that will make them want to open their drivers? What's going to outweigh potential patent etc. risks?
Because, as far as I can see, they gain basically nothing. They might get a "good news" article or two but it won't increase their sales significantly at all.
Are we still in the era of hoping that huge multinational companies will do complicated, expensive, liability-affecting things for us out of the goodness of their hearts if we complain enough?
I would love them to, don't get me wrong, but I can perfectly see why they - and others - don't. There's no advantage to a network-card manufacturer not having their network card drivers in the kernel. They don't do anything secret, they operate on well-defined protocols, they all pretty much do the same things, and you can't even start up a computer properly nowadays if your network card isn't supported from the first minute. So the open-source code is next to nothing anyway.
But graphics card drivers? What's in it for nVidia? Will they sell more video cards? No. Can you not boot your machine without an OS driver? No. Can you just use the proprietary drivers? Yes. Is card X that operates at 10billion IPS almost identical in operation to card Y that operates at 100billion? No. Not even close.
And then you have to have OpenGL / Mesa / CUDA etc. drivers, APIs, libraries, etc. All this doesn't affect most kinds of hardware but for graphics - one of the fastest moving technologies - it does.
So I can't blame them. And I can't think why they should beyond political idealism. And I can't think what the OS community could do to change that.
If OS ruled the world and could decree such things and nobody bought things that weren't OS-approved, sure, we could bully them into submission. But we don't work like that.
So what can we, as a community, provide to nVidia to convince them to open themselves up to potential patent lawsuits and huge developer expenses on a regular basis?
I can't think of anything.