I would like to  address on the point "the ends don't often pan out".  It appears that the issues you have discussed are involved with failures of instrumental reasons and epistemic failures as opposed to problems with consequentialism as a moral system.  I believe learning from these failures don't necessarily  involve in history but can be also achieved from alternative sources. For example, a mechanical engineer would learn about Challenger disaster. Similarly, a nuclear engineer would learn from Fukushima disaster.