I'd wager that probably plays a large role.
Additionally there's been several leaks of our spies' identities, by foreign countries but also by our own people to get back at others. Consider Valerie Plame [1] who's identity was leaked by the Bush administration folks: Richard Armitage, Karl Rove, and Scooter Libby, apparently to target Valerie's husband. While Libby went to jail, the group still had a receptive journalist in The Washington Post who similarly had no qualms about revealing the identity of a spy, regardless of danger or legality. Actually we tend to treat journalists as a "higher caste" not to be questioned: "Of course a journalist has the right to report on <any|every-thing>!"
I don't think the same environment exists in our country as in the old days where it'd be "safe" or attractive to be a spy.