Bees build these sheet structures from wax they secrete from abdominal glands. In thw wild, they fill all avalilable space, allowing just enough room to move around the combs. The sheets hang on branches, occupy cavities in trees, and of course, form on frames supplied by beekepers. Any less space, and the bees can't easily move around. Any more space, and the bees build comb, which could block man's access.
Good spaces make good neighbors.
The System Bees are great engineers. They create a working system of circulation, moisture control, and air flow. If possible, they bore air vents in the top and bottom of the hive. They fasn their wings to move the air around. They also keep their home dry by fanning.