True when dealing with a human workforce. Not convinced it's equally true when dealing with an automated workforce. That being said, I don't see why self-sufficient villages is something to strive after even it could be done efficiently.

If efficiency is not an issue, I definitely think self-sufficiency is something worth striving for. Makes you less dependent on outsiders. You're not suddenly in trouble when you get isolated, and because you don't strictly need anything from the outside, outsiders hold no power over your village, making it less likely to be exploited in unfavorable deals. Self-sufficiency would go a long way to addressing structural inequality.

It's not about efficiency, but about variety. Life gets pretty mundane when you have to eat the same damn foods for every meal.