It's easy to be principled when you're not calling the shots yet and not confronted with all the realities of the choice.
I imagine once Obama was in office, he was told what had been accomplished so far using this kind of intelligence (terrorists killed, plots prevented, lives (allegedly) saved, etc) that the US would give up if the intelligence dried up. Who will chose to accept that attacks might happen on your watch as President when the tools to avoid them are already in hand?
Yes, but it's clearly illegal to search everyone under the constitution, so these sort of advances in counter terrorism should never have been allowed. Hard to argue with tracking everyone once it's happening without uproar, I imagine it's very very useful.
I imagine once Obama was in office, he was told what had been accomplished so far using this kind of intelligence (terrorists killed, plots prevented, lives (allegedly) saved, etc) that the US would give up if the intelligence dried up. Who will chose to accept that attacks might happen on your watch as President when the tools to avoid them are already in hand?