United States v. Reynolds was the first time the US government invoked the State Secret Privilege when a group of widows sued to obtain an accident report after a B-29 crash. The government insisted that the accident report contained classified information that was vital to national security and thus, could not revealed to the widows.
After the automatic declassification and release of the accident report in 2000, it was revealed that the report contained no such classified information and the government likely chose to not release it out of embarrassment, not fear of national security. This American Life did a really great story on it.
That document is hilarious. Some of there were obviously misunderstood and used as guidelines for organizational effectiveness by our government clients!
It’s much easier and more secure to stamp certain depts and actions as classified rather than having someone look through them all and go “yes, that’s definitely bad, yes, that coud be bad, no, that’s fine, yes, that could be bad if taken in the wrong way,” etc.
This is just my WAG but it seems likely.
Also, some of them coud have seemed like security risks at the time and we now know they aren’t, but they didn’t live in 2014.