This is the thing though. The cables were extremely embarrassing to the US and damaged international relationships, but they didn't really disclose any new crime that was committed.
At the time, the US Government was prohibited by law (Smith-Mundt Act of 1948) from propagandizing the American people. This was repealed by the Smith-Mundt Modernization Act of 2012 which allows US Citizens to be exposed to propaganda.
Notably, one US Government strategy for propagandizing is to disseminate/test the stories in the British press and wait for them to be picked up by the US press. This strategy is still used even though the Smith-Mundt modernization act makes it less necessary for legal compliance.
Wikileaks revealed that the US Government withheld and classified information solely for propaganda purposes. In other words, a small group of people deceived the public so that a very expensive and consequential war they wanted to have would not be interrupted by common sense insights that the public would have had.