A common definition of insanity regularly attributed to Einstein is
"It’s often said that the definition of insanity is doing the same thing over and over and expecting a different result."
People are looking at this wrong.
Passengers are going to take the luggage if they have it.
Accept it.
There is no point in raving about it. The majority don't read Pprune or give a cr@p what you think.
You don't know what is in the bag and how much they perceive it to be worth to them.
If I had £10,000 in my bag, there is every chance I would take it with me. Maybe my wife's ashes etc etc etc. You don't know.
Ranting about putting others at risk is pointless. We all do that every time we speed on the road, but everybody does it.
The only way to solve this problem is to remove the issue.
Locking overhead bins are an obvious idiocy.
No hand luggage will solve it, but is the cost/benefit worth it?
How many lives have been confirmed lost through people carrying off luggage?
There are a thousand things we could do to save lives in airliner crashes that we chose not to do because we don't care enough at the end of the day.
What's the big deal about hand luggage?