I have a pet theory/headcanon that there must have been a Droid uprising at some point in the Republic's past and so restraining bolts and memory wipes are part of the culture around Droid use. Sure they are useful, but they get upitty... The existence of IG-88 and other "evil" Droid strongly suggest they can gain free will or at least go bad.
The SW universe having its own version of the Butlerian Jihad lines up well with the spice references Lucas borrowed from Herbert.
It would also help explain why space fighters still have pilots instead of being just straight up piloted by droid brains.







