Three thoughts on bags:
First, returning some years ago from a long haul first class with KLM, my hold bag was overweight for the short-haul back to the UK on another carrier. The check-in lady at AMS instructed me to put lots of things in my (not to be weighed) cabin bags. I pointed out the hazard this would pose in causing burst lockers etc and she looked at me as if I was a nutter. The problem seems to begin with corporate behaviour, as this lady exemplified.
Two, we provide pilots with an error-tolerant environment, where their normal, error-prone, behaviour, will not cause catastrophe. Why do we not consider providing our untrained, frightened, passengers, with an environment in which they too can err, and try to keep their belongings with them in an extremely stressful situation?
Three, the tombstone imperative tells us that this will not change until and unless there are many deaths. Each evacuation in which passengers leave the aircraft with their belongings and without awful consequences justifies the status quo, rather than evidences the need for change.