Needs to be revealed? Totally, where it exists. Deterrent? Hardly.
You seem to forget the invisible line of power and privilege that protects the elite from being sent to prison. GWB committed known felonies during his presidency. The CEO of Massey Energy negligently murdered a number of his employees. Madoff might have gotten caught, but neither his wife nor sons were convicted, and meanwhile Goldman Sachs is doing some incredibly unethical stuff that may or may not have helped to wreck our economy, and that whole institution gets off scott free for the price of some kabuki theatre in DC. Oh, but hey censure Charlie Rangel if it makes you feel better.
We have a good deal of press freedom here in the States, but unfortunately the mainstream media reports on the wrong news, everything now has to be yellow journalism (the wars of left vs. right, Fox vs. MSNBC, etc.) and people in our society are way too uneducated to be mad at the real injustices in the world, like the power our plutocratic overlords now wield. I doubt 10% of our nation knows what the Citizens United verdict was, but you know they're damn mad at the world about the fact that they have to pay taxes for art, because let's rag on a few billion and completely sidestep the trillions that is going to pay for blowing up brown people in the middle east.
Besides, IANAL, but some Internet-distributed leaked classified document probably doesn't hold up in any legal courtroom, so how is anyone going to be punished, exactly? No.
Deterrents don't exist in this country, because in order to deter someone from doing something illegal, you have to actually convict them. And you can't do that in our society anymore.