c) that's due to the OS, isn't it? Those technologies have no hard dependencies on Win32 API, unless I am mistaken.
b) I would not stake my business on that, personally, I believe hard dependencies on OS dlls are obsolete technology, philosophically, and I'd seek remedy if possible -- re: WPF, etc.
a) XAML beats the dog snot out of the UI in Winforms, it is a much better programming model.
My perspective is optimistic. Changes to WPF, Silverlight, WinRT are responses to community demand and technological best practices. Every single iteration of deliverables are welcome here. I will state that most of my own pain working around these type changes were due to poor code designs on my part and not from API modifications. That's my experience with .NET and it is not the same experience I had with other languages.
Ah, you have dirt under the rug... to wit: "as long as tablets aren't important"... ah-hem. Obsolete!
I do appreciate your perspective, but I'm not sharing it.