Passengers, just like pilots and CC, are human beings and react in different ways to emergencies. There will be heroes and there will be people who want to take a bathroom break (FFS, I'm astonished at that one).
I'm in Skeleton's camp. If there is an evacuation and you are looking for your duty free gaspers and are in my way, you lose.
We often see pics of incidents like this where pax have their hand baggage. The KTM incident is another one in the news right now, rucksacks and all. But are there studies of passengers' behaviour? Do the authorities look back and say, "Hey, a lot of the pax took their hand baggage, we ought to be concerned about this."?
Or do they just shrug their shoulders and say, "Oh well, it was alright this time."??