An accident is often preceded by a chain of unexpected events leading to the calamitous loss of the aircraft.
Hence we have accident investigation to provide the facts leading up to the event which in turn can be used for safety training leading to the prevention of the same said circumstances leading up to the accident.
Learn from the mistakes of others as you don't have time to make them all yourself.
The fact that these pilots were investigators is not 'ironic' it just shows that these sad events can occur to even the most experienced and prepared of aviators.
Perhaps though this could be a salient lesson to all those pilot managers who think they are more prepared for emergencies even though they fly far less than the line swines as they read all the incident reports?