Americans now possess (or more accurately are possessed by) a vast "intelligence" bureaucracy deeply in the shadows, whose activities are a mass of known unknowns and unknown unknowns to those of us on the outside. It is beyond enormous.
Many documents produced by the U.S. government are confidential and not released to the public for legitimate reasons of national security. Others, however, are kept secret for more questionable reasons.
Overclassification actually threatens national security by limiting the sharing of information among officials and agencies. More fundamentally, overclassification undermines the critical ingredient for a well-functioning democracy: an informed citizenry.