Do you really believe that "doing the right thing" is the primary goal, or the secondary? Obviously that's how it's sold to the public, but it's hard to deny that espionage isn't the real goal.
Terrorism is a convenient trope to get people to willingly relinquish their liberties, just like "for the children" but with the goal of deploying ubiquitous scanners, drones, and microphones instead of censorship schemes.