From what I know so far, I think, they are trying to remove the burden of the developer of making so many apps of the same kind for the different gadgets. Eg. Making one app to be used in smartphone, tablets and desktop, rather one app for each of them.
I just don get it, mircosoft created a YouTube app using their own time and money, but google say they can’t cause it has no ads and videos can be download. WTF? There is so many apps out there that bypass the ads and helps to pull videos from YouTube. And yet google is not saying about them. “Ok fine then,” says Microsoft, "but we need a YouTube app like the one you give it to iOS " . Google says" no you can because you platform do not have so many users it will impact my ads reveune and you can use a moblie website YouTube." F*** the m.youtube.com I say . It does not give even the half the experience on iOS or android for god damn sake. This is discrimination against window moblie platforms! I want a solid wp YouTube app!