Thanks for sharing your insights. For the UX/UI designers out there working in Sketch, I got into designing for VR by way of this simple Sketch plug-in: https://blog.prototypr.io/sketch-plugin-sketch-to-vr-4e23ced47e6#.aujwi2r4j.
The plug-in creates a simple web-based VR environment using A-Frame. This is ideal for light-weight VR prototyping because A-Frame is simply HTML. It has a fairly robust documentation and is under continuous development. Learning it took a lot of trial and error but I didn’t need to learn a gaming engine like Unity or Unreal. A-Frame is also optimized for HTC Vive’s room-scale.