Define "technical requirement". It's not really technical, it's political. As an end user, I couldn't care less about being able to inspect how the code works. What I would like is for Linux to have a stable API for drivers, so out-of-tree drivers could work on every release without DKMS or crap like that. Windows could do it, so it's definitely not a "technical requirement".
If they are afraid of getting bug reports from guys running out-of-tree drivers, they can still keep using the "tainted" mechanism. It is not incompatible with having a stable API.
If they are afraid of getting bug reports from guys running out-of-tree drivers, they can still keep using the "tainted" mechanism. It is not incompatible with having a stable API.