@etiles I agree that your findings are weird indeed, anyway I think the main point is a truly representation on the gradient embracing the meaning = extremes (black and white good) and gradient (gray are bad - sort of). Looking at an entire scene at least, it makes sense.
I wouldn’t call it a bug, but someone didn’t just consider that there was another visualization for roughness (someone sloppy maybe), so for coherence it should be the same, I hope someone see our comments and check this, I wouldn’t make a bug submission report just for that.