Just because something is strictly legal doesn't mean that it's right, nor that it's in the spirit that the law originally intended. I mean, it was legal to exterminate Jews in Nazi Germany, send millions to death camps in Soviet Russia and starve 10s of millions to death in Communist China.
Strict legality is particularly low bar to pass. What happened to the spirit of the law? What happened to public discussions of the law? What happened to proportional use of the justice system? What happened to basic human rights?
Maybe I'm just naive, but when people hide behind the "Well it's legal! A secret court said so!" charade, even when they know that that it doesn't follow the spirit of the laws that they currently operate under, it just pisses me off.
It's kind of like when someone cheats a system using a secret loophole that was clearly not intended to be used for that purpose. The person then turns around and says that it's a perfectly legitimate move. They then move forward on the assumption that the mere existence of said loophole gives them carte blanche to just do whatever they hell they want to do.
It appears as though the NSA has hacked the legal system.