now that is a great idea, do you know if any other cameras/lenses do this? That makes so much sense (so much that I think focus by wire might some day be much more comfortable to use than direct mechanical focus). (would be cool if the new sigma mirrorless lenses that will hopefully soon be announced also did this, maybe even user adjustable)
It would be cool yes. As a Zeiss glass user, I might say that "focus by wire" have some road to do before getting even close to real smooth and precise mechanical focus (like Zeiss or old AIS Nikkor Lenses
So yes, it can be more precise when coupled with scale in live view (like the DPs) but mechanical focus isn't just about precision, it is also about feeling and coupling. So, lens manufacturers should work on focus ring feeling coupled with the electrical rotor. AT the end, focus by wire might be the future, as well; I think it is really possible.
And, for the mirror-less branch of SIGMA lens, I'm not sure they will provide docking support as they do for DSLR lens, at all.