Autonomy on is my default state, because I want to see my sims to weird/surprising things, but the ai/programming (?) behind the sims isn't very intelligent, so they end up doing stupid/repetetive things instead.
I was testing to see how much influence traits had on autonomy and gameplay objects yesterday (spoiler: not much), and locked my sims in a lot with a fence, testing indoor and outdoor activities. I gave the arty sim clay, which they left outside in winter (unfortunate), and because all sims obsess over it, the least creative froze to death when he wouldn't stop molding it.
The amount of times I had to cancel a sim-destructive action during that session (did not want to make another replacement sim), made me almost long for playing with autonomy off. Almost.