But right now, you have the limitation of not being able to make the same modification to multiple objects at once---people asking e.g. how to move a wall, and have the room boundary move with it. I don't think that scenario rises to the level of advanced usage.

Yes, modifying vertices can break the consistency, but most of the time the adjustments would be straight X- or Y-axis aligned. And the time to use a tool like this would ideally be before walls are cut anyway.

The main reason that I want this is so I can lay down walls using rough measurements, and then be able to adjust everything easily later on when I get more precise dimensions. Right now, I have to have all the exact numbers up front, because changing things after the fact is way harder than it should be.