Consistency is good because it means fewer things to remember, and that code is less likely to break when one piece is swapped out for another. It's not circular at all. I don't think consistency is the most important goal for designing something, but it's a goal.
Anyway, the case where this matters most is stored properties, not locals, but I wouldn't want to change the behavior for stored properties and not locals, because that makes the special case even smaller.