I think there needs to be an acknowledgement that the NSA, the FBI, and the government in general are not staffed by angels or robots, but by human beings, and that some of these human beings are criminals. The very fact that Snowden got all that data means that, regardless of whether or not he's a criminal or a whistleblower, the humans in government cannot be trusted with this data. "The FBI" may have a need for this data but the humans in the FBI are too great a risk. I find it absurd that we are even having to have this conversation with an organization that has to deal with operational security.
Few men could be moral when offered the combination of unrestricted power over others, total secrecy, and lack of consequences for actions, that is so often the state of these agencies.
That's why we need their power to be limited and defined, as open as possible, and have legitimate avenues of redress for grievances. They are supposed to be public servants, not rogues.
