As with walls, the software numbers opening as they are inputted. If you delete or add opening your numbering can get out of sequence.
The wall renumbering allows to manipulate the wall number to suit drawing layout style. For example, using grids.
When searching for a particular opening on a large floorplan, it seems easier to locate opening when they are in some kind of sequential pattern, be it clockwise around the perimeter walls of whichever system you like. Being able to renumber them just gives flexibility.
Another way might be if we could simply output the opening number to the database when outputting lists.