Professor Thomas D. Beamish analysis of the Gulf of Mexico Platform Heritage Disaster, “The BP Disaster and the Hobson's Choice of Oil Production” has been published online at ClimateProgress.com and MIT Press
Part of the answer is that BP had joined the group think of the oil industry and truly believed a blowout disaster was 'inconceivable,' 'unprecedented,' and unforeseeable. If you can't conceive of it you can't prepare for it. Another reason is the voluntary, "trust us," self-regulatory regime that BP and Big Oil demanded and received under the Cheney-Bush administration.
Beamish is uniquely qualified to discuss these issues. He is Associate Professor of Sociology at UC-Davis and his areas of expertise and interest include complex/ formal/informal organization, economic, and environmental sociology. He is author of the book "Silent Spill: The Organization of an Industrial Crisis" (MIT Press).