Truly sensitive information about FBI, ATF, CIA, etc. communications should remain classified, but the vast majority of government bureaus should operate in the open.
This is really part of the general problem of "over classification". Bureaucrats ALWAYS believe their work is a matter of national security, even if they're doing clean-up at the National Zoo.
Encryption should be available to federal enforcement agencies such as FBI, ATF, Secret Service, etc., but NOT agencies such as NWS, NPS, BLM, etc. no matter how "sensitive" their bureaucrats think their own communications are.