I imagine these arguments usually come from a perspective that the US should be as weak as it would be with all its cards on the table; possibly coupled with the idea that if we're spending $500b/yr on defense, going down a few rungs on the power ladder still leaves us above everyone else. It's a very populist idea--that we can trade tactical power (the kind you get from having secrets) for strategic power (the kind you get, supposedly, by having the average voter participating in the decision-making process.) Let alone that the military isn't under congress...