Hypothetically, a benevolent NSA would primarily develop cryptographic security tools for the populace.
I know there are some judges and institutions that enabled this madness, but I think they might be guilty as well.
These judges should be accountable to the public in theory.
I am not saying the everyone working at the NSA is a criminal. But maybe Snowden was the only one with perspective.
The NSA as an institution certainly did more damage to the US than most of its enemies.
The US has judges and legislation to enable the NSA.
Russia, China, Iran, NK, and many other authoritarian states seek to use their power to attack America 24x7 and do so without any oversight.
Personally, I think the "cyber war" is the typical scare to reduce civil rights. That is a pretty common pattern to bolster and justify disregarding the law.
In reality, the cyber war is probably still focused on the classical industrial espionage. I fail to see the need to subject citizens to mass surveillance.
When society has no great way of preventing, let's say for example, the Boston Marathon bombing or the Las Vegas Concert shooting, providing an appearance of activity, however mindless, like a bunch of ants feverishly running around when a stone is thrown into the anthill, is just the default setting of the security establishment. You can't blame them for that because we aren't yet psychologically, socially or politically sophisticated enough to do anything better.
But today after collecting and sitting on top of shitloads of useless data they themselves admit its unnecessary. You don't find who the best Tennis player in the neighborhood is by monitoring the entire neighborhoods conversations but by just watching the local tennis courts.
What you can do is ask why it took so long, with that nudge from Snowden, for the establishment to admit this. That kind of questioning prevents them jumping into further "we can do it so lets do it" bullshit projects down the road.
(IIRC / I believe)
Many would disagree with that perception, and I also believe that amount of surveillance to have been wrong and counterproductive, but there hasn't been any evidence or significant hints into possible corrupt motivations.
One mustn't forget that all of this was put into motion after the 9/11 attacks, and both the Bush and Obama administrations where still working under (somewhat irrational) pressure from citizens afraid of a repeat performance.
We could better say there is no indication that nobody who had access to illegally-obtained information misused it.
We have plenty of evidence of cops misusing databases they have access to, and that stuff is way less juicy.