It's not useful scrounging up, uh, conspiracy theories for how it happened unless there is evidence.
The only argument you're invoking is abduction - that no other approach fits the facts. But the thing about the NSA is the level of spying and power that's demonstrated gives a strong indication they just don't have much reason to care what the public thinks. The average NSA bureaucrat isn't worried about the public at all but what argument their boss or colleague will use against them. And letting out information goes so hard against the default impulse that letting information out intentionally seems way unlikely, even as part of a clever master plan. I mean, if we're wandering to wild speculation land, the NSA has dozens of potential master plans. One that releases information and makes them look bad wouldn't do well in the "master-plan competition" - held yearly at Area 51!
Why would Obama sanction deeply-embarrassing revelations and expose the staggering depth of warrantless spying?
This is almost certainly not the case, but that's the answer that came to mind when you asked the question.
That being said, I'd be surprised if that were the case here. But a man can hope.
I still think it is extraordinarily unlikely though.
One thing about spy movies and the CIA, they're truly masters of misdirection. While you're watching the world fawn over Snowden and what he's done and the fallout, you can bet these people are still 4 steps ahead, planning and plotting their next move.
Who? The government? That is like believing that super advanced weapons have been developed by the government that no other scientist/engineers could hope to replicate because the Science and technology are so ahead of their time (i.e. 50 or 100 years).
What if Snowden is still a CIA agent (he was a CIA agent for years before NSA) and this is actually a snowjob/whitewash by the government to deflect attention or essentially control the message about news they knew would be released (diffusing that/controlling that message) and black-ops about China, Russia, Cuba + Venezuela how they treat/process possible 'traitors' or spies?
I hope that is not the case and he is sincere, it would be great if the US could just pardon him and address our Constitutional issues. But if they pardon him doesn't the above seem like an outside possibility?
Or am I reading too much Tom Clancy and watching too many spy movies?
It does seem most whistleblowers are swept under the rug but here you have one that is garnering lots of news and attracting lots of attention across multiple weeks/weekends to things that were previously labeled 'conspiracy' or only seen in movies (yet have been in the news quietly before, since 9/11). Now it is international news everywhere. He is almost the perfect leaker, making more waves than all combined.