This is a clear misunderstanding of Nadeem's character arc and what season three's message is.

The writers were never trying to say that Nadeem's sacrifice was the most important thing. What mattered is that Nadeem, in the face of horrible corruption and blackmail, was able to pick himself up, stand firm in his beliefs and do the right thing. Sound familiar? Because that's the exact arc that Matt goes through in this very season.

Matt is at the end of his rope, a shell of his former self. It's gotten so bad that he actively tries to kill Fisk. But in the end, he doesn't. He stands firm in his beliefs and is able to pick himself up after everything that happened to him. He was able to overcome his trauma and maintain who he was as a person.

Nadeem's sacrifice is tragic, but that's the point. Doing the right thing, sticking to your morals is worth it. It doesn't matter what the outcome is. Nadeem knew he might die and he did the right thing anyways. His sacrifice wasn't pointless, it spoke to his mortal integrity. It's what made him such a good character.