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.
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.