I propose the idea that double clicking on a building, just as you can double click on a unit, will allow you the ability to select all instances of that building. This will decrease the amount of time one has to spend in their base during a battle when commanding troops a certain way can be critical to the success of the fight's outcome in your favor.
Also, being able to select more than one building as you can with units would probably be helpful as well, and then having the possibility of using the hotkey command on them would help considerably.
*Edited after notification from moderator to be more clear.