What Windows needs in way of user interfaces are not more pieces of flair but actual improvements in interaction that would make it possible to use touch, pen or mouse and keyboard everywhere in the operating system. When Windows 8 came out, the support was half-assed for either.
They did restore the mouse and keyboard part a few bits in Windows 8.1 and then more in 10 because mouse and keyboard is what users were used to using and were yelling the loudest at Microsoft for.
But even now after the latest Windows 10 update, trying to perform anything but the most basic of basic tasks on a Window tablet using only touch or touch and pen is a very frustrating exercise. For instance, most standard apps and dialogue boxes, such as in the File Manager and the Control Panel are still made for mouse and keyboard only.
A pen or a mouse (and sometimes a physical keyboard) is therefore still a necessity
It's sad, really. I can still not recommend a Windows tablet to anyone, no matter how fast the CPU is or how much RAM, storage or pixels it has.
Windows 8 became available to developers in 2011 and available to the public in October 2012. That's four years - that's ridiculous!
Oh, I'm sorry, I forgot... Windows for Pen Computing came out in 1992! Knowing Microsoft's that's probably older than the (inexperienced) programmers who will be tasked with whizzing up Metro.