In a discussion of the nature of leaks and leakers, a point is made that is not often made:

The deeper threat that leakers such as Manning and Snowden pose is more subtle than a direct assault on U.S. national security: they undermine Washington’s ability to act hypocritically and get away with it.

This is the truth not only of whistle-blowers, but many of our secrets:  It is about protecting us from the consequences of our own hypocrisy.