Personally, I think the manoeuvre limits can't just be a max pitch and roll figure - you can create more stress pulling up harshly to 30 deg nose up than you can pulling smoothly to 60 or even 90 - it is the rate of change that does the damage but that isn't factored in to the RFM/RTS.
Nothing wrong with 90/90 as pitch and roll limits - it is how you get there that creates the fatigue.
One solution would be to fit all helos with G meters so at least you have some empirical data to work from rather than just guesswork.
It is the sloping ground landings that will have caused the long term fatigue and the final act of landing out of limits with some less than perfect control inputs as the straw that broke the camel's back.