Now if only they had a better way to design UIs than using clunky XAML. WinJS + CSS I think is a little better, but still not comparable to what iOS or even Android has.
It is a fantastic experience for a designer compared to what you get using only visual studio
PS: Apple and Google don't care about developer's experience as much as Microsoft does, they just care about customer's experience.
It's probably because Android's format was originally designed for simple keypad-operated mobile layouts, and then was painfully extended for touchscreen applications.