(This is mostly a joke, but the performance of NTFS for certain operations has always been abysmal, and having a virus scanner injecting itself into all the operations only makes it worse.)
You might be able to model that stuff as xattr, but then it could be problematic to mount that ext4 partition into Linux because applications might be copying files without respecting the xattrs.
Well, since Microsoft has been borrowing more and more ideas from the Linux ecosystem, it would not surprise me that a Windows 10 successor would include some kind of compatibility layers for different file systems.
We can dream...
I wonder about the bigger part of this question.
What are the higher-ups saying?
I wonder if this is like the IBM PC, which was a GOOD THING invented by a sort of an offshoot of IBM culture. Then IBM higher-ups stepped in and tried to control the platform (PS/2, OS/2, microchannel, etc)
WSL is attracting people to windows. But the endgame isn't to lose them to linux. So they have to tie it into windows more. But if they make it too slow and bloated they might lose.
an interesting situation.