I'm currently working on several VR projects and have come to discover just how slow the iteration loop can be for seeing the materials/textures in a head-mounted display. Since Allegorithmic is already ahead of the curve when it comes to glTF support (
https://www.khronos.org/gltf/), it seems natural that they'd also embrace cutting-edge display technology.
So much is gained from actually seeing substances stereoscopically-- things like gamma, normal maps, and mipmapping can often appear slightly differently in VR. Being able to iterate within Designer or Painter before exporting everything is essential for smooth production.