The insitutional, rank and file feds are totally insulated from public outrage anyway, so they are free to do as what pleases themselves.
-- Which is a terrible reason to hide what they've got. --
Might be the best reason. What if the public was given evidence that in no uncertain terms, JFK was assassinated by the CIA. Tell the truth, or lie to the public and try to clean house in the shadows?
Well, yes. My belief is that the government has done a lot of bad stuff. JFK being an example. I think the current “unhappy path” might lead us to Civil War due to divisive politics. But maybe if we knew the truth, we’d be heading for something more like an actual Revolution.