The major factor is obviously the fear of Microsoft lock-in, I think. Which is reasonable.

If it's more about the technical details, such as general issues regarding cross platform UI frameworks, I think we're way past that point considering HTML5/Js :)

Every single time I am forced to do web development, I miss such frameworks.

What does that mean? The web is already cross platform, that's kind of the whole point

It means the Frankenstein of CSS/JavaScript/HTML tooling, still catching up with the 4GL RAD tooling of the 90's, or expressive native environments like Microsoft Blend, iOS and Android native layout managers.

Or the lack of integration with native animation frameworks, widgets, behaviours and system APIs, even with HTML 5.

Or hacks like Service Worker with in browser database, to be able to write offline apps, something that just works out of the box in native apps.

Right now, it's only on the roadmap.