There's also a lesson in there for the "this sucks, they're all corrupt" type nihilists. It turns out that it was possible to be a lot more corrupt, and that things could indeed become much worse.
When executive agencies have separate bodies for investigation than enforcement (e.g. the NTSB, independent of the FAA and NHTSA, and the CSB, independent of the EPA and OSHA) they tend to be very capable, with investigations that are very thorough, transparent and scientific, and result in excellent recommendations to prevent recurrences.
Executive agencies that act as regulator and investigator (the DOJ, SEC, FDA, etc…) tend to be much less capable, reacting to the first thing they come across, finding someone to publicly take them blame, then signing secretive negotiations where no one admits to any wrong doing. It is an environment that invites corruption, but it's not caused by corruption, as eliminating corruption would not create good results. A well run, and transparent investigation, where public safety is prioritized over posturing, would create much better results.