On the issue of people taking bags with them its not right but is it preventable-people react in different ways under extreme stress and no matter what laws are in place may do the 'wrong ' thing. The only way is to reduce the amount of hand baggage on board from the ridiculous amount sometimes seen. In one of the pics on this thread a man in shirt is carrying what looks like a full size case from the burning plane.
I was on board a BA short ahaul flight in the exit row last week and the FA was very diligent about bags not being allowed under those seats much to the chagrin of the American pax sat next to me -he commented different airlines different rules but I am not sure who allows under seat bags in the exit rows in any country so despite seemingly a frequent flyer he was either unaware he was in an exit row or ignorant of the rules.I suppose if I was really nasty i could have called the FA back and said my seat mate isnt a suitable person to be flying in an exit row..
So you cannot stop this behavour but you can try to improve it- re inforce it in the briefing -cut down the ditching bit if you have to as there are seldom any ditchings anyway (or 'landings on water' to use the ultimate oxymoron ) .
Also encourage through publicity , travel agents , internet sites etc to keep your passport with you or, better yet, take a pic and store it on your phone as most people are surgcally attached to their phone and make sure immigration authories are properly briefed to treat accident victims as just that and not terrorists. Even the TSa might understand that the bad guys are unlikely to have peoplel in place on USA bound flights all a round the world 24/7 so someone can slip into the country when an accident happens saying -my passport is on the plane and it got burned.
People panic in spite of endless entreaties from cabin crew, police and Corporal Jones because it is NOT a controllable response -if it was no one would panic-so educate a lot and minimise the risk because you cannot eradicate reactions to risk completely.
PB