[pjmlp]

Because it uses C++, and C++/WinRT tooling for UI development isn't there.

The team that killed C++/CX, said it isn't their problem that there aren't Visual Studio integrations like C++/CX, and eventually left C++/WinRT in maintenance and nowadays is responsible for windows-rs repo. Better not expect too much from that repo as well.

Welcome to Microsoft politics.