The New York Times editor explains himself:
We get to decide (to cover the documents) because America is cursed with a free press. I’m the first to admit that news organizations, including this one, sometimes get things wrong. We can be overly credulous (as in some of the reporting about Iraq’s purported Weapons of Mass Destruction) or overly cynical about official claims and motives. We may err on the side of keeping secrets (President Kennedy wished, after the fact, that The Times had published what it knew about the planned Bay of Pigs invasion) or on the side of exposing them. We make the best judgments we can. When we get things wrong, we try to correct the record. A free press in a democracy can be messy.
But the alternative is to give the government a veto over what its citizens are allowed to know. Anyone who has worked in countries where the news diet is controlled by the government can sympathize with Thomas Jefferson’s oft-quoted remark that he would rather have newspapers without government than government without newspapers. And Jefferson had plenty of quarrels with the press of his day.
As for why we directed our journalistic attention to these cables, we hope that will be clear from the articles we have written. They contribute to our understanding of how American foreign policy is made, how well it is working, what kind of relationships we have with allies and adversaries. The first day’s articles offered the richest account we have yet seen of America’s attempts to muster a regional and global alliance against Iran; and disclosed that the State Department has increasingly put its diplomats in the uncomfortable position of gathering intelligence on diplomatic counterparts. There is much more to come. We sincerely believe that readers who take an interest in America’s conduct in the world will find this material illuminating.