The side effect of doing so is that anything that anybody could ever possibly need could be fulfilled at the same time. Nobody needs DRM, despite what the MPAA, and RIAA would have you think.
And then there is the issue of blue sky. Blue sky is just a term meaning extra cool stuff. Can you provide blue sky in an open driver? Thats debatable, but I believe it can.. Blue sky should be implemented in hardware, and controlled by a firmware. Take power management for example. Some degree of power management is required, the minimum for the open driver would be some form of clock scaling. But if you wanted to provide a better system of power management then it should be implemented in hardware and controlled by a firmware.
I think we've all seen the benefit of a similar system, that you've described here called AtomBIOS... A similar system to provide blue sky would be ideal, and would still allow for an entirely open source infrastructure. It would easily satisfy all of your customers who have mistakenly claimed that they need a closed driver, and would also satisfy the vast majority of other users who will need the open driver.