In the process of removing the rotting teeth, let us not cut off the head.
Please note that these are NOT top secret documents. They are embassy cables with a much lower classification. If we are going to hang Assange out to dry for merely disseminating this information (Hannity, etc. have also done so as a I said), we need to also include journalists and pro-war politicians in government (and out) who rountinely make selective use of similar documents to rationalize their behavior.
As to your other point, if we define "national interests," as advancing American national defense, rather than policing the world, nobody has named a single example in the documents which undermines that goal. In fact, they advance that goal by, for example, showing that the public optimists on the Afghan quagamire are really pessimists in private who think Karzai and his government are a hopeless case.
Again, what is your altenrative to expose these and similar examples of government corruption, bungling, and hypocricy? Are you suggesting that "investigations" by Congress or the President will do the job?