Why do we need this bumbling spy agency again?
We don't.
Why? Espionage and other spying is moving to the digital realm, and we need to be able to match/overtake our adversaries. The NSA has arguably the most sophisticated surveillance apparatus in the world and it's going to become increasingly necessary to both fight back and defend our networks against Russian and Chinese aggression.
Clearly they have internal issues with keeping information safe among employees, but that's difficult to solve. Given the issues the NSA has faced since Snowden, I imagine they are putting more effort into this, but it will take time.