The maximum restriction of 23kg per bag, and the punitive "Heavy Bag Charge" which doesn't actually generate that much revenue (the old excess tariff per kg yielded far more cash!) was indeed put in place to protect the baggage handlers - indeed, if airlines followed the EC regulations to the letter, anything over 25kgs should be banned altogether as we do not have mechanical handling facilities at all of the airports we serve, or use for diversions. (Due to commercial considerations, First, Club World and BA Gold and Silver cardholders (but not One World equivalents) are allowed a maximum weight of 32kg per bag - the number of bags allowed depends on the route and ticket type.)
Health problems associated with continually lifting bags in excess of 20kg have been discussed ad nauseam. As a youngster, I helped neighbouring farmers to load hay bales on to trailers during the school summer holidays and I now have a pronounced lump in my back. Darling daughter's student boy friend has a bad back after last summer's job transferring baggage between connecting coaches at a motorway service station.
As I have often advocated here, there is a whole world of difference between lifting bags in and out of the car boot for that once/twice a year holiday and manhandling them every day at work - sometimes crouched on knees in sweltering heat in an aircraft belly! The discomfort and desire to get out of the heat quickly can lead men to forget the manual handling techniques they have been taught!
(Bing Bong Boy will probably chuckle if I mention "Dip and Drive", "Big Engines" and "Look After Your Doughnuts" because he will know exactly the BA video I'm talking about!)
The problem is that spinal or nerve damage has a nasty habit of being, at best recurrent, at worst permanent. Your help in keeping the individual baggage weight down is appreciated!
There is also the necessity to reduce the quantity of hold baggage passengers are allowed to take in readiness for the A380 which can be configured to carry twice the number of people a 747 or 777-300ER can carry but with a similar volume of cargo/hold space. Hopefully, now that air travellers are getting used to the idea of moving around the globe with less deadweight, the New Large Aircraft will not pose too many challenges as they get taken on strength.