Great food for thought, Jeffeb3! I am often referring to Artificial Intelligence as Artificial Stupidity when it gets it wrong. I seem to recall Dui ripped out his S42B closed-loop steppers when they began fighting each other.
Issues of noisy sensors, too-slow feedback loop, data overload if processing images, are all good points you make. A wider safety margin on an open-loop system may be the right answer for now.