KBPsen
As far as I know the industry had been asked to provide input to develop more realistic limits. Apparently airlines declined to even respond to the request and manufacturers, as their customers appeared to have no interest, maintained the zero tolerance policy. So did the regulators.
It seems airlines played the game of passing the buck and regulators and manufacturers saying fine have it your way. Until the ash hit the fan and the airlines were all caught out by their own dithering. And of course blamed the regulators.
a fair summary
If you want expert opinion than you have to remove the threat of liability. This routinely is the case where the industry acts within the existing regulations. If you ask somebody with deep pockets to work outside the regulation you get what you pay for.
I'm not sure how far or deep the questions went within the industry, but the manufacturers were certainly asked to shoulder increased risk with little to gain.
I do agree that the operators were the losers in this, but hopefully they will develop a quicker response next time now that they know that the regulators and the manufacturers are not about to accept monetary risk for the way someone operates.