Indeed, though my recollection of Feynman's most pertinent criticism is that he suspected that the probability of failure of the thousands of individual compone

Indeed, though my recollection of Feynman's most pertinent criticism is that he suspected that the probability of failure of the thousands of individual components - probabilities that are all very small numbers - were picked with one eye on how they moved the overall risk. He felt that the analysis, which should have been bottom-up (and nominally was) was actually conducted in a top-down manner. The space shuttle program demonstrated that if your analysis overlooks just one scenario (such as a rigid O-ring or ice on the bipod ramp), the risks can be much greater than you calculate.