Really bad example when the war crimes revealed were actual murders etc. of many, many civilians, and Assange’s crime was telling the secret (by the rules of a country that he was not a citizen of, and of a country where he wasn’t located) that these war crimes happened and that nobody faced any consequences for them.

Revealing information about many murders is very different from doing murder.

The problem here is that Assange didn't kill any people, while Uncle Sam has killed hundreds of thousands for oil, revenge, and preserving the hegemony.

Getting a plea deal is contingent on the state caring about the larger crimes in the first place. See the problem?

The Iraq and Afghanistan war logs revealed significant crimes. In my view, the worst was the significant misrepresentation of civilian casualties, the level of involvement of Iran in the conflict, torture and abuse tolerated by the US. In general, the war logs revealed that the US Government had classified information specifically because releasing it would have likely led to Americans opposing the war. There was no justification for classifying most of the information other than that the truth getting out would have turned public opinion against the war.

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 This was repealed by the Smith-Mundt Modernization Act of 2012 which allows US Citizens to be exposed to propaganda.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.

A helicopter gunning down civilians and journalists.

The Iraq and Afghanistan war logs were a highly significant piece of journalism that revealed significand (and in my opinion treasonous) misconduct by US Government officials. See my description in another thread:

https://news.ycombinator.com/item?id=40800817