People forget that before UWP, there was the Metro/Modern application platform for Windows 8 and now it's dead. What's telling us that Microsoft is not going to come out with some new API next year and kill off UWP? I mean, it's not like the platform has been without criticism; some big name game developers are already calling for the death of the platform, and tying the platform to the Windows Store when nobody actually uses the Windows Store or knows it exists doesn't exactly capture my heart as a developer. (Not even Apple can do that on the Mac.) As much as I dread using Qt, GTK, wxWidgets or MFC, I would pinch my nose and use those for now, and then cross my fingers that Microsoft gets things right for the UWP sooner than later. I would love to use the UWP for my project but as it is right now it's a no-go.
On a side note, I don't get why people dislike the CX language extensions so much. The objects of the UWP class library are glorified COM objects, and the CX extensions simplifies their manipulation as well as the creation of new ones, so why not make it easy on you and use those when you deal with Microsoft APIs? It still feels very much like C++ and is so much easier and convenient than the nameless mess that you have to deal with on competing platforms to get C++ to play well with the OSs. (Namely, JNI on Android and Objective-C on Apple.)