Ubiquitous surveillance can be used to control and coerce anyone, regardless of absence of criminal wrongdoing (though there are people who claim the average american commits three felonies a day now, because the USC is so overbroad).
It's not about "nothing to hide": when anyone can be blackmailed, including judges and lawmakers and law enforcement, the entire system of interlocking checks and balances breaks down.
Worse than threatening to expose MLK's private life, they wrote to him as if someone from his religious community found out about it and shamed him and suggested he kill himself.[1] So not just blackmail, but psyops.
As I wrote in another comment, it's not just surveillance for state purposes, it's also surveillance for the corporate interests of the state (pharmaceuticals, agribusiness/GMOs, oil lobby, etc.). What if the big 3 auto makers were so powerful that they tried to crush Tesla by subtly targeting its customers and employees with fake bad news (oh wait, maybe they're already doing it). I'm convinced that some of the spying on the EU was over agricultural policies such as their strong anti-GMO stance--US companies would love to have advance knowledge to maneuver around them. I'm not sure it's happening yet, then again, how would we know?
I wrote this the other day, explaining how Obama confirming ubiquitous surveillance in the US (even if it only targets foreigners (which turned out to be a lie anyway)) is a bullet in the head of the US internet industry:
It's not about "nothing to hide": when anyone can be blackmailed, including judges and lawmakers and law enforcement, the entire system of interlocking checks and balances breaks down.
http://pastebin.com/7SRmFpFH
The FBI threatened MLK Jr with exposing his extramarital affair (they'd discovered via surveillance) if he didn't give up his civil rights work.
You may not have anything to hide, but many do, for entirely legal reasons, and it is shameful of you to deny them their right to privacy.
If you truly have absolutely nothing to hide, it is quite unlikely you are doing very significant work to meaningfully improve the world.