Ask HN: Why don't hotels let you pick your room?

Does anyone know why I can't pick my actual hotel room when I book a room? I want room 807, not 805 or 806. Now you can do it with planes, you can select your actual seat. I want that but for hotels. This would be especially helpful to me as I usually need to book two connecting rooms for my family and it NEVER works out no matter what I do unless I call 24 hours in advance and make sure they are connecting and even sometimes then I have to go up to the manager and complain and threaten to leave before they manage to get two connecting rooms.