I know what is API. I am computer programmer myself.
I understand MS point.
But I don't think that some developer would make an app, just because it can be used on Xbox. They are too diferent
platforms.
What I don't understand, why kill mobile platform right after you created UWP.
Just because the API is available on multiple platforms, doesn't mean devs have to take advantage. Of course, they could do this easily, but they don't have to. But for the sake of this discussion, it's irrelevant.
It's easier for MS to maintain a single API than a dozen different ones.
If given the choice of writing an app against Win32 vs. UWP, and UWP can do everything that Win32 can do, is there any reason to specifically use Win32 still? And if thats the case, MS can remove the legacy Win32 code, and that's far less code for them to maintain.
It's a win for MS, and in its current form, nothing is made more difficult for devs (possibly even easier, though I haven't looked at it in a while), so there are no real disadvantages.
My point is, don't think of it as being for universal apps (or more specifically, mobile apps), think of it being the next-generation API, that just so happens to work on multiple platforms.
The main feature of UWP (to developers) is that its an updated, modern API for Windows applications. The universal part is just a bonus.
Right now, yes, that bonus is a bit if a waste without a mobile implementation (and yeah Xbox isn't suited to all desktop apps). But its just a bonus, not the main feature. The API itself is the main feature.