Why does Microsoft want this?
I guess so they can make Windows Phone run iOS apps? I really doubt that will change the eventual fate of Windows Phone.
Intel has dropped a slab of code into Microsoft's Windows Bridge for iOS project, starting with APIs for vector maths, matrix maths, digital signal processing (DSP) and image processing. According to an announcement posted at Microsoft, Intel wants to make sure that developers working in Objective-C can run their code on Intel …
I think, officially, it's so that iOS apps can more easily be ported to Windows Phone and to mainline Windows. So frameworks like this are reproduced identically as they're just processing things, intended to allow work to get done. However Microsoft intends to provide distinct UI libraries that merely conform to an iOS coder's expectations on patterns and idioms. So you still end up writing a native Windows application, you just do it in a language and using a language binding that was not previously supported and which more easily facilitates conversion. You definitely don't just hit build and get some pretend-iOS sandbox that kind of connects to the Microsoft equivalents of some things in some places to some extent.
Because if you can reasonably easily turn your iOS app (iPhone or iPad) into a Windows UWP app, you can target all of Windows 10. XBox, Desktop, Laptop, tablet 2-in-1 etc. etc., not just phone.. That's a big and growing market in total. I'm sure a lot of developers would like more sales from that.
Because if you can reasonably easily port your iOS app (iPhone or iPad) into a UWP app, then you can target ALL of Windows 10. XBox, Desktop, Laptop, 2-in-1, tablet and even phone. In total that is a large and expanding market. If you're making apps to make money why wouldn't you want to do something not very hard, that gives you access to a larger market?
How useful is the typical iOS app going to be on a Windows machine with a mouse/keyboard? About as useful as the typical PC app would be on a smartphone, I wager.
Getting access to a larger market is fine, but apps would need to be rewritten, not just ported, for anyone to actually find them useful outside of Windows Phone.
This project will be dead in a year or two, tops. What iOS developer would ignore the much larger Android market to go through the trouble of porting their apps to the windows 10 platform? If they haven't ported their apps before it's because it simple wasn't worth it, and that's not going to change anytime soon. Only thing MS can do is just pay developers to port their apps.