I have to disagree. Without the cameras capturing this attack, the cops woudl have diddley-squat to go on, other than what the victim could recall. I would think a camera has a better memory that someone being whacked in the coconut repeatedly with a bat. Had the victim been killed, the cops would only have the corpse for evidence.
That said...
The distinction we need to look at is privately owned and operated cameras vs. government-controlled surveillance. No one would advocate preventing banks and businesses from putting up cameras on their own property, and these cameras quite frequently capture images of suspects that can be used as evidence to prosecute them.
Were the cameras in that story controlled by the property owners, or the city?
I'm 100% in favor of allowing property owners to put up as many cameras on their property as they want. Granting the same power to a bunch of busybody politicians? Yeah, I don't think so.
But, yeah, the idea of a camera "protecting" you is pure folly.