I have had to do the unload bags thing twice now, on both occasions I was told it was an H&S thing. It is the way of the world, whilst airlines make money from excess baggage, I think more and more they are also concerned about the costs incurred due to work related injuries. Don't forget, on most airlines, 32 kg is still 9 to 12 kg over the economy baggage limit, soi they can still have a go for excess baggage. It is just a case of diminishing returns and they have worked out that 32kg is the optimum limit.
Putting a HEAVY label on a case would not always have saved the woman mentioned in the (very long) article above. I have been through several US airports and Osaka where the baggage screening took place before the baggage was weighed.