I thought DX11 was general enough now that direct code wasn't used any more? All calls from major games go through the DX driver on Windows as far as I know. Also it might sound attractive to bypass that extra 'layer' but really you will not see speed gains from direct access, it's too hard to do for complex game engines.
DX is actually fine to implement on non-MS platforms, since hardware support is there, all they need to do is write new libraries for it instead of using MS's code.







