Whistleblowing is good when actual wrong has been done, but governments and businesses cannot function without privacy any more than individuals or families can. When people don't feel comfortable talking off the record, or when they fear they might be endangered by it, they stop talking, and mutual misunderstanding and suspicion ensue.
Take the revelation that Hillary Clinton had inquired of her aides whether Christina Fernandez was on medication and if so, how the meds affected her decision-making. It's a perfectly legitimate question for a secretary of state to ask before meeting the president of a foreign country. Yet Ms. Fernandez is hardly likely to be pleased to learn that it was asked, and this makes relations between Argentina and the US ever so slightly more difficult. Much worse would be the consequences of harsh words used by US diplomats (in a confidential discussion) about the chief Chinese representative at the Six-Party Talks over North Korea, and the revelation that some American diplomats think an important Turkish minister is a bit of a closet Islamic extremist. Publicizing such matters makes the going along the rough edges of international relations just that much rougher--and makes the world a slightly more dangerous place.
Back on the home front, what good purpose is served by making public the knowledge that some American diplomats in Colombo, at least, believe that President Rajapakse and his military commanders are guilty of war crimes? It is not as if the news is going to change the views people already hold. It may briefly put fresh heart into human-rights campaigners and civil-society activists, but its practical consequences are all negative: they consist mainly of increased friction, distrust and resentment between Sri Lanka and the US, and between Sri Lanka and the west in general. It will make working towards final reconciliation and accountability harder than ever. That benefits nobody.
'Freedom of information' also means freedom for information to flow. By turning itself into an obstacle to its free passage in this way, Wikileaks has made the world a shadier, more secretive place. This is nothing less than a terrorist attack on civilization. It will have a far greater impact, in the long term, than 9/11 ever did or could. And it is not just the West that is the victim here. It is everybody.