It's important to note that discussing the content of a classified document - even if that document has been leaked and is in the public sphere, and regardless of whether or not the information really should be classified - is punishable by serious jail time. This effectively prevents public debate about any program considered "classified", which means if you're doing something shady that would be embarrassing if it came out, you just slap a security clearance on it and claim its for "national security", thus precluding any government officials from acknowledging it.
As more and more government programs are considered classified, the people are given less of a voice in how our country is run. That is the most scary part for me.