Thanks for your input. I wanted to clarify the "Multiple devices" portion of this thread, as many were jumping over the primary advantages of off device Luci. Yes multi management can be done to the extent you and others are referring to, but lets walk before we run.
Like others said before, this would in fact be architecturally challenging for LuCI. It is an excellent idea, but your chances of getting this implemented are equally like of developing a new UI from scratch. Quite literally. You would have to entirely refactor LuCI for this.