Tom-- Its crucial from the golfers standpoint to know whether you are in a bunker or not(calling it waste area, transition area, etc is not crucial so long as its clear that it is different than a bunker)--
Lots and lots of significant differences under the Rules (touch and move loose impediments, sticks, stones, etc in a "waste area", not in a bunker; ground club in waste area, not in bunker; perhaps embedded ball relief through the green(depending on your wording of local rule), not in bunker; can move sand to search in bunker, not in waste area; relief is totally different from immovable obstructions, ground under repair, unplayable ball in bunker vs through the green--much more liberal relief rules through the green)--
If it returns to its "natural state" its not a bunker--
I'm not saying which it needs to be, but its got to be one or the other and whatever it is it does need to be clearly defined.