Revealing what is in those documents might threaten US power projection in the world, but it would not threaten US national security in any significant way. That is, it might hurt the US' ability to shape the world as it desires, but it would not make the US significantly more vulnerable to being attacked because no matter how much people know about the NSA's activities, groups that want to attack the US would still be confronted by the US' overwhelming national security strengths of being surrounded by huge oceans, having a nuclear deterrent, and also having the world's most powerful conventional military.

I can imagine there being classified documents that pose an actual significant national security risk. Perhaps some details about how nuclear plants are secured, or the details of the mechanisms by which authorization to fire nuclear missiles is given. Stuff like that. But there should be nothing like that in the NSA documents. Maybe there is something in there that would tip people off about the NSA's encryption-cracking capabilities. But no system that is actually critical for national security should be vulnerable to such information being revealed. And if there is some system that is vulnerable because of it, more surveillance is not the answer anyway.