Assuming rational decision-making by people who were just involved in a plane crash is a completely irrational assumption to make.

If you lock the overhead bins people will spend time trying to unlock it. If you try and stop someone from bringing their bag they are likely to just lash out at you for getting in their way in survival mode. In fight or flight mode with adrenaline pumping you don't hear someone yelling at you to stop or yelling at you to let it go - you look out for yourself and your own survival. Not because you are a bad person but because it's a natural response - you can say 1000 times you would act differently but you don't really know until you actually are in that situation.