Would you like the job of Director at the Bureau of Economic Analysis in the United States Department of Commerce? You need Top Secret clearance.
This fact naturally raises the question of what the BEA might be doing. Do econometricians at the Commerce Department commit murders, suborn perjury, or record titillating images of innocent citizens in their bath or bedroom? Those would be reasons that other agencies have Top Secrets, but it is difficult for me to visualize any econometrician I have ever known engaging in quite this set of practices.
Perhaps the BEA has embarked on quite a different path. There are plenty of economic crimes, after all, ranging from market manipulations through economic slavery, from destabilizing foreign governments to funding domestic political campaigns.
Historically it has seemed easier to justify secrecy for agencies which are not intended to further the free flow of information. Secrecy would seem to be discordant with the mission of the Bureau of Economic Analysis and such discord ought to invite public scrutiny.
If the discordance can be minimized, such scrutiny is less likely. If all of the Government directorships require Top Secret clearances, disharmony becomes expected, for example. In that case, even though the discord persists, attention is distracted away from the the particular instance, the BEA in this case. Alternatively, the level of discordance can be reduced by adding elements to the agency's portfolio with which secrecy is believed to be more harmonious. Most blatantly of all, the Government may attempt to persuade the public that secrecy at an agency charged with providing public information is not disharmony at all, but rather a form of atonality which the common citizen has not yet learned to appreciate.
It does not matter much whether the citizen does not think to ask or is too abashed to ask, so long as the citizen in fact does not ask what sort of crimes might be hidden behind a Top Secret clearance.
This is how the game is played, in actual reality.