It is very difficult to use the context sensitive action (space bar) to open doors and perform other actions. This is because it can be difficult to target the door like the game wants you to. In the heat of combat, this can be detrimental. If I'm looking at a door, I should be able to press space to open it. I shouldn't have to look at a very specific part of the door, or stand far enough away from it, etc. In buildings like the barracks, often the wrong doors opens when you try to open one.