Make WPF Cross Platform
Make WPF built apps work on the big 3 (Windows, Linux, Mac). This would make using Visual Studio and the WPF framework a slam dunk for UI tasks!
As it is, I am using WPF primarily for prototyping (by only one developer). When it comes to actual development we ditch Visual Studio and use cross platform frameworks and IDEs.
I want to personally thank you for taking the time to share this suggestion. The WPF UserVoice forum can be found at https://wpdev.uservoice.com/forums/427690-windows-presentation-foundation-wpf.
Program Manager, Visual Studio
I second this suggestion. Since WPF is built using DirectX, it should be possible to change the back-end to OpenGL to make it cross platform. Currently, there are no real client side application UI solutions.