D3D is not controlled by Nv or AMD, thus either is able to use it without needing to worry that the other has undue influence.
Of course, but the similarity is that both D3D and PhysX are just eye-candy (in response to your comment about being "stuck" with effects physics).
I'd be willing to bet I'm not the only one.
No you're not. But I suspect the number of "enthusiasts" who take up a cause against Nvidia for this is smaller than the number who will just see PhysX as some extra thing only Nvidia has. The fact that people are pissed off goes to show that they feel like they're missing out on something. If they didn't care they wouldn't be mad in the first place. Sucks for people who prefer AMD hardware but that's the whole point of product differentiation isn't it?