Let me tell you something: No matter what you do, evil always finds a way. And when it does, do you really want to live with the regret that you could have done more, but chose not to for fear of some imaginary future evil?
We can estimate the severity of the negative consequences of mass surveillance and censorship across the entire country or globe and compare that to the smaller number of isolated, but perhaps more severe cases of evil. We can then choose which we predict will be the better state to live in.
Here in America we do that with guns. We do that with cars. We do that with natural gas accessible in the house. We do that with electrical lines that may sometimes get damaged and kill someone.
The answer is yes, we can say that the cost of mass surveillance and censorship is too high to pay for a little safety. If that means that someone I love is killed, or my home is broken into, then so be it. It will be tragic. It will hurt. But at least we will be free.
I'd argue that so far, the cameras are working in our favor. Police abuse gets caught on tape and prosecuted. Political corruption is harder to hide. A white supremacist who murders someone with their car and speeds off is caught. The Saudis get busted murdering a journalist.
I'm not sure we can honestly estimate the negative consequences of mass surveillance. Certainly not if we lump every camera in to that category; I wouldn't want a camera in my living room, but I sure would like a camera pointed at my parked car. Streetlights? If it stopped my car from being broken into for the fourth time, I'd be pretty ok with it.
Here in the US, it's not for want of camera technology that we are not living in a police state. If anything, the cameras are helping keep our social institutions honest.