Nobody makes "decisions" like this in an organization with the level of complexity and bureaucracy that the CIA has. A lot of these decisions can be seen more as emergent behavior, subject to politics, short-term immediate incentives, and the pragmatic observation that any attempt to make significant changes (i.e. "change the laws around classification of documents") has such a high time horizon that it's better to bypass the law than try to fix it.
All of this makes more sense when I imagine smaller groups within the bureaucracy with narrow objectives and severe myopia trying to "solve" immediate problems to achieve short-term objectives. It makes my skin crawl to contemplate but the truth is that human beings do this sort of thing all the time.
I think you're right as if you look at behaviors as the result of a rational decision-making process, it seems the sort of "decision" only an insanely self-destructive person or organization would make
