The industry must take the lead on this. It is a problem induced by the policies of airlines themselves, not customers. We can't blame a regular family for avoiding the expense of discretionary hold baggage charges. They WILL bring maximum cabin baggage instead if they can. It is just common sense.
Nice to see an intelligent post. The industry should have stamped on this marketing ploy (creating headline prices based on over more creative upselling policies) as soon as it appeared. It is human nature to reduce cost if it is possible - even wealthy people do this by deeply ingrained habit. It is also human nature to protect ones important belongings and finally it is human nature to act irrationally under extreme stress.
If the industry wants an increased safety margin where baggage is concerned the answer is 100% in its own hands.
Set a common standard for carry on baggage and enforce industry wide. The rest goes in the hold. Airlines can price it however they want, but not alter the standards. I'm sure there will be someone along to say it's not possible...but frankly it really is that simple.