Check out pictures of the evacuation of the Twin Towers and most are carrying briefcases / handbags etc. It seems to be a natural reaction and perhaps it can't be prevented?
Many of the people evacuating there were still on their way into work so didn't stop to pick up their cases etc.
Another scenario to give to people would be Manchester. How many of the victims there would still be alive today of they had a few more seconds to get out the door? Many people died there because of smoke inhalation just seconds from the door. I am in no way saying that baggage was to blame on that one but pointing out a few seconds delay because a bozo (or 20) in front of you decide to go to the overhead to retrieve something can make all the difference.
If your that worried about your passport etc, keep them in your pocket. If you want to keep them in your jacket pocket you should make a choice. Leave the jacket on until after TO and then put it in the locker or leave it behind and get the hell off the aircraft without slowing anyone else down.
Final option for those that want to take their bags is to wait until EVERYONE else is off the plane before you go to the locker.