One of you CSM's who are planning on retireing should spend the last month or two traveling with a set of digital bathroom scales. Set them down by the door and weigh any larger bags and line up all >7kg ones in the bridge and refuse to carry them in the cabin.
It would annoy a lot of people but you'd force a change and make me laugh at the same time. It could be your legacy
(In addition, you may save some kid from having his head stoved in during an over-run or turb some time down the track).