Consider if everything you do in public is taped.
Then consider that a team of 1.000 people monitors you and you alone, everywhere you go, everything you do.
Then imagine what that says about you. About where you work, where you shop, what you buy, which friends you keep, who you bring home etc.
Then think about whether you're cool with this 1.000 man team recording this in a database, to be potentially used by the government. Consider your familiarity with historical and current governments who have abused this for purposes ranging from ethnic cleansing to political oppression.
And then consider that in the world of computers, that 1000 man team costs a few dollars of computing power at some point. Facial recognition combined with a whole range of data (from your cellphone being registered, to your financial accounts making transactions being registered, to your car being registered, obviously your home and workplace, and social media networks detailing your network, and your communications being monitored).
The combination of this all is incredibly dangerous. Should we worry and fear? Well it depends on one question, which is 'do you think your government will ever shift so incredibly to actually abuse this'. If the answer is yes, then there's no escape and our lives in relation to tech as we know it today is incredibly dangerous. If the answer is no, and you also don't fear individual gov users illegally abusing their privileges, nor hackers abusing the gov systems, then you're good.
But again that question has nothing to do with whether we should hate CCTV or not. The question is do you think it'll be abused. If the answer is yes, then CCTV is incredibly dangerous.
Now about the question of the chance for abuse... Well I'm totally not paranoid, indeed I generally feel quite optimistic about these things. I live in the Netherlands and I don't think we'll make such a shift towards abuse on a large scale. At the same time I live in a city that commemorates the 'terrorist' attacks on the civil registry during WWII by the resistance movement, because jews were being processed for genocide with these records which detailed where ethnicities lived in Amsterdam, and the resistance sought to destroy the registry to prevent it. They succeeded but unfortunately they held a copy in another city. And that's relatively recent history, in my parents' lifetimes, in one of the otherwise freest societies on earth.
It's largely because of this reason that many countries don't have a civil registry. For example here in the Netherlands we don't hold a census because you can simply pull the information from a database, it's like Facebook doing a census on the age of their users, it'd be silly. For the same reasons one may wonder whether CCTV cameras which can help track people in similar ways, combined with other information, makes sense.
That doesn't mean I don't think the cameras' benefits outweigh the risks, but for me to say they're completely harmless would be myopic, too.
The 'it's public space' I think is a weak argument against mass surveillance. Humans can't live without participating in public spaces, you can't remain in private space and live a full life, so we must ensure high levels of privacy in public spaces, too. Just because a space is open to the public doesn't mean your privacy is.