To have a down arrow for down-graded room attributed booking when the upper categories are temporarly overbooked.
This would be very useful. At the moment you can upgrade rooms with an up arrow and easily move them between categories. To downgrade the room you must change the space category, this can be very confusing as to what room type the guest actually wants/booked. We downgrade guests from a twin room to double convertible often, and all the extra movement leaves room for errors and misunderstandings.