This has happened to me multiple times already- a raid/animal attack happens and someone has left something, eg a bucket of milk or basket of rice, in the frickin' doorway propping it open. Suddenly you have a gaping hole in your defenses. It'd be nice to have doorways as areas where nothing ever gets dropped, I'd take the occasional overflow inconvenience over security issues.
I 100% agree. I understand how feasible it is for things to be dropped in doorways, but it causes a huge problem for colony's that are struggling to survive. I can't say I've ever lost a colony to an open door, but I've definitely had one set my progress back quite a bit by expiring a bunch of food I thought was being cooled properly...
I once had a massive prison break occur because someone dropped a meal in the front door of the prison. The fact they dropped it because I'd drafted them to fight a raid should tell you how interesting things got after that.
<irony> Oh no .. this would also prevent the exploit of incapacitaded pawns or animals in doorways !!! </irony>
=== EDIT ===
added tags .. sorry . .