Why? WSL1 was kind of interesting indeed, but WSL2 is just a VM, isn't it?
It's just increasingly silly in the Azure and server space to be running Windows--you lose all the benefits of the container ecosystem and have all the baggage of decades of windows cruft (yes I know windows containers exist--no one uses them). Desktop usage has been in decline forever and I have to imagine they could get the 90% of windows API apps left that matter to work great on wine. It would give Microsoft a huge boost to get back in ARM by building on the linux kernel and its great support vs. windows ARM very limited set of qualcomm and a handful of other chips.
If they were to discontinue Windows they would just be throwing away those billions of dollars in annual income.
Since Windows continues to make Microsoft such large amounts of 'easy money' they would be stupid to not keep pushing it out to customers.
Plus theres the simple reality that Microsoft's got native APIs in Windows that enable running a linux vm with a KDE window alongside the standard windows environment. Microsoft has really come a long way and that's what's really amazing and kind of disorienting.
These (and more) result in the end-user interacting with WSL2 the same way they would any normal application. To think of it as simply a VM isn't quite correct.