There are numerous signs that Wikileaks had an important influence in the events in Tunisia, Egypt, Bahrein and Syria.

> Didn't Americans democratically elect a government which estimated that keeping diplomatic cables secret was the right thing to do?

Assange isn't an American citizen, therefore he can't be a traitor to the USA.

> Didn't Assange publicly release those cables?

Yes, and ironically they significantly enhanced the opinion that the rest of the world has now on USA diplomacy and policy. So it actually both profited the USA and the rest of the world.

> That being said, he certainly promoted freedom of speech.

Exactly. Some people (like me) states that social forms of freedom are more valuable than anything else. Some others value authority, or morals, or other things higher. You could take the "political compass" test to know better where you're situated. I myself is in the bottom left, a rabid leftist-anarchist; I'm quite sure that Assange fares quite similarly.

http://www.politicalcompass.org/