I respectfully disagree.
I want body cameras to fix the right-now-today-real-world-conjoined-twin problems of police brutality and illegitimate complaints against police. I'm willing to address the small risk of mass surveillance separately from this.
I understand fully:"Those who sacrifice freedom for security receive neither." I do not see widespread decentralized use of bodycams as a threat to the former. That can be controlled trivially with judicial oversight.
That leaves a question of extrajudicial acquisition of the footage. That might be a problem if we were considering a nationwide program where all of the recordings were dumping into the same datacenter, but we aren't. The implementations we see today have recordings stored separately by each department, most of them in offline storage. That's nearly ten thousand discrete systems that would have to be penetrated and harvested by the NSA. The risk of this appears quite low.