I remember when DirectX was a huge obstacle to porting games to Linux. This feels like a great, great victory for Linux to me!
[0] I use this word specifically because it's a martial art about using an opponent's strength against themselves. MS's use of Chrome as the basis for their new browser is another example of this.
Why?
This is not DirectX on the Linux desktop, it is DirectX for WSL. This means that code written for this will NOT function on desktop Linux.
Additionally, support for DirectX for WSL is support not spent on Vulkan and OpenGL.
Like CUDA, I assume that most applications would not be coded to this API directly. Microsoft already mentioned OpenCL and OpenGL.
This is to hardware accelerate Linux applications and not to create WSL-specific Linux apps. I can't imagine there's a big market for Linux GUI apps that would only run on Windows.
You won't be able to take this dxgkrnl driver and load it into a Linux workstation and get DirectX.
And also, someone else responded to you what's the point of running Linux if Windows can do everything Linux can.
I would assume that most full time Linux users are using it out of at least a tiny bit of ideological motivation. And if not ideological then habitual, having had the power and granular transparency of Linux for so many years that Windows would never be an alternative.
Running Windows has never been an option for me, since Microsoft went down the "activating Windows" path many, many years ago.