Better than the worst isn't a favorable comparison. And there's been attempts but they lie and dissemble at every opportunity to the oversight committees. Remember when they tried to redefine the word 'collect' to mean when they actually looked at the information so they could say they don't 'collect' information on american citizens? Or that gathering information on every call you make isn't surveillance because they don't collect the contents of the call as well?
https://slate.com/news-and-politics/2013/07/nsa-lexicon-how-...
If you don’t like the way NSA is governed, change it. That’s the power of a democratic system. But when the choice is between autocratic and democratic intelligence agencies, the choice is clear.