I believe a single (direct) fire arrow hit does destroy the cameras in Thief. Think I learned that while playing some random fan mission, just decided to try it for whatever reason. As you mention, they're insanely loud anyway, so it's more or less the final solution.
I also wouldn't mind water arrows having some form of effect on the cameras, at least electric ones. If you dump enough of them on one, it wouldn't be too out of reach to expect a reward. Just like you can disable the hulking security bots in Thief 2 with some water.
That said, I find the classic Thief 2 "disable everyt