It suddenly dawned on me: When talking windows development, Microsoft didn't take any chances and provided 2 options XAML and HTML, but when Nokia chose the new platform it did take its chance and went with Windows Phone only.

BTW, I think Microsoft acted wisely by offering HTML/CSS alternative, because since its inception so many years ago, XAML didn't produce any killer apps. None. It might be the most advanced framework for UI, but it sure didn't leave its mark.