In my opinion:
- The main advantage is preventing people from ruining their registry.
- The 2nd advantage is using the OpenXR own native means, for doing exactly what was the registry editing workaround provided for.
- The 3rd advantage is when OpenXR decides implementing another way, they shall support backward compatibility with the Environement Variable
- The 4th advantage is that you can easy set this for all users or just you.
There are certainly other advantages and as many disadvantages but one thing for sure: OpenXR has a specification for overriding the driver you’re using and this uses the Environment Variable, not the registry, per their official docs.