I'm not trying to wrinkle anyone's shorts, but this just makes a lot of financial sense. Let the "community" do most of the OS development and only maintain the Windows UI. This allows them to focus more on services and Azure.
Microsoft has already gone out of it's way to take control of the hardware and kernel (think secure boot on intel and the _total_ control on arm). They're now allowing you the privilege of running some posix userland applications (which have no real power) so people don't complain too much when they make it impossible to boot a custom kernel on newer hardware.
"What do you mean you can't boot linux? Don't be silly, you're already running ubuntu!"