Future maintainers, who could be you. It has happened to me a few times, and I thanked my past self every time.
It doesn't even have to be clean code. Sometimes I'll even settle for understandable code. In my experience, however, few people care about this. My most common comment in code review is "add doc" or "add explanation"
But why would you want to wear something like this, for that? I can see how an editor/IDE plugin might be useful (a la racer for rust etc) - that would update a section of the screen with tips - but I don't think I'd like to have this on a completely different device.
Now, with a full vr headset, it might make sense to be able to place such things outside of the normal field of vision (where your text/code editing resides) - but so far I don' think working full time in VR with text is a great idea, with the current generation of headsets.