"My sole motive is to inform the public as to that which is done in their name and that which is done against them." - Edward Snowden.
It's that "done in our name" portion. We run this gin-joint. Our spies have performed illegal operations.
He could have leaked the information with proof regarding the tapping at AT&T, Verizon, Google, etc without releasing information that damaged our foreign intelligence gathering.
That's actually quite a lot of effort that entire news corporations are STILL shuffling through. Years later. And what if he slipped up while censoring the data? You'd trust one man without a budget and a limited time-frame rather than an organization with a QA department? Or I supposed you'd rather he enter Russia with all of the NSA's as-of-yet unreleased secrets.
And do you honestly believe that anyone at the NSA could have influenced ISIS's surge to power? Really? Do you honestly believe that IF ONLY Snowden hadn't blown that whistle, then somehow the NSA would have prevented the clusterfuck in Iraq right now?