I am somewhat disgusted by the level of hatred being exhibited by people towards whistleblowers. The notion that "people in authority" should have the sole responsibility to decide what is best for us to know and not know is antithetical to the idea of democracy. Dislike it though you may those "random people" are and always have been our best chance at uncovering abuse by authority.
The people in authority have every reason to conceal information that is damaging to them. Do not put stock in the fear-mongering rants of government PR propagandists. They **** bricks and spit fire if someone leaks a diplomatic cable.
While I have not yet looked at these documents as I understand many, if not all, of the Afghan war documents that named people were not actually classified documents and the names may have even been publicly released long before. Certainly I haven't seen a single report suggesting any person has actually been killed or harmed as a result of that leak.