Personally, I believe that if something needs to be kept secret, it's because it shouldn't exist or be happening in the first place. This is my extreme idealism at work, and I admit it's an idea that isn't immediately compatible with the world as it is. Regardless, the reason military operations need to be secret, is because they're about fucking killing people. Whether it's hiding corruption or strategical information, the reason it's relevant is because it's about doing harm and there lies the conflict. It wouldn't be so damn important if it wasn't, at its core, evil, even if necessary evil, which is an extremely subjective and questionable concept anyway. The only reason anybody cares about the diplomatic cables is because they reveal the games that people are playing with our lives. Nobody gives a shit if Diplomat A insults Diplomat B behind their back, but they do if they're doing so because Diplomat B is somehow endangering people. This is information that people want to know out of personal concern. If it wasn't, people wouldn't care, and nobody would care if it was kept secret or not, including the people keeping it secret.
I believe in personal privacy. For instance, I really do not give a shit that Clinton cheated on his wife. He may have been the president, but that was his personal life. The stuff we're talking about, though, is public affair. In professional life and public issues, secrets are problems that exist, and the people responsible don't want the people concerned to be aware of these problems. In the context of this discussion, I am completely against keeping such secrets.