Its happened several times to me, and I'm sure to others, we are under attack and order everyone inside, so our traps and such can do their jobs, and some fools just HAVE to go stand in the doorway to welcome the invaders.
My last fortress, before it flooded, killed 50 out of 60 attacking goblins, before they could take 3 steps thru the front arch. But sadly, I had 5 killed, because they just HAD to go pick up something graciously donated by its former owner who had no further need of it. Would have been far more, but I managed to draft several and order them back out, and then locked the door. But soon as I locked the door, the remaining goblins, who had no trolls with them, started walking away.
It would be great, if we could designate an area like the front hall, as being a "forbidden area", so the dwarves would stay out of that area, like they would stay away from the outdoors when ordered inside. It would also be very useful for clearing out farm and forest rooms, before they are flooded. and even for channels, so we dont get fools "racing the train".
I would like to save my troops and people for the real bad guys, not have them killed by a bunch of wussie goblins. Thats just embarassing. I'd rather leave my traps deal with them. (Tho I did meet a not-wussie-at-all goblin axe lord, who managed to swim a channel halfway from the chasm drowning room, to a bridge that crossed that channel in my nobles section, over near the river. He then, even tho he had no weapon, still managed to kill 4 people before he was killed. Goblin or not, he gets a salute from me! Wonder if a klingon was visiting, and got mistaken for a goblin?)