As a thought experiment, are we certain these documents came from Snowden? He has not digitally signed these releases. He himself may not know entirely what was in the archive, so he may not be certain if all the released documents originated from his dump. Even if he was aware of documents being incorrectly attributed to him, it may do his cause more harm than good to highlight this fact.

It would be a legitimate option for the NSA to intentionally "leak" documents that simply describe their mission, causing a false spectacle. It will not hurt them much, given it's well within their mission parameters, but CAN hurt Snowden through public backlash. It would raise such questions as, "is Snowden still a whistleblower?" Such releases could hurt his credibility, or even flood the news with insignificant stories such that the truly important ones are lost in the shuffle.

I am not certain this is what we're seeing, but neither would I be surprised if it were true.

EDIT: There have been documents leaked about how the CIA and IC use character assassination to advance their causes. There have also been articles explicitly about the character assassination of Snowden: http://www.prwatch.org/news/2014/06/12522/glenn-greenwald-sp... http://www.securitycurrent.com/en/writers/richard-stiennon/t...