[bitwize]

There are tradeoffs with that, too. The moment you provide low-level access, you make whatever low-level interface is supplied a standard to be supported now and forever. See: the VGA, or any of the Amiga chipsets. One thing that may fall out of this is that future GPU vendors would provide the low-level interface as an abstraction over what's really happening under the hood. And then developers will complain that they can't take advantage of the the real chip's theoretical capabilities.