cockney steve,
In the 172 I used to drive there were several AD's about leaky exhaust mufflers, chafing of fuel lines, flight control mis-riggings to give just a few examples. The DC10 cargo doors is a more extreme example of where poor, but certified, design led to disaster.
So I am led to believe we can agree that AD's is a good safety tool, n'est-ce pas?
What you seem to take issue with is who_pays_for_it. Despite everyone's best intention to build a safe product (minus corporate corruption - e.g. the B737/787 whistle blowing) things seem to be certified and later proved it wasn't working as it should. If the manufacturer promises to take care of all future AD's isn't it reasonable that this "unlimited premium warranty" will up the price of the product slightly? A bit like buying a car with 100 year warranty.
Or the airlines buy a plane at a cheaper price knowing there is a possibility that certain components will need to be checked/replaced - at their own cost. If I buy a car I expect to cough out for some unexpected maintenance whatever it could be. It's just in aviation this maintenance can sometimes be premeditated to avoid the dire consequences should something be left till it fails by itself.
I see your point of view. My message was simply that AD's are there for good reasons (..some better, some worse). Then how the peanuts are being passed around I couldn't really care that much about, it will settle itself when all profit maximization seeking organizations have had their say.