Because self-sufficiency provides a much lower standard of living than what you can get with trade and specialization.

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.

Agree, I sometimes wonder how much of this is just a manifestation of our fear of the unknown.

Consider, the world before the internet when the postal services was doing all the heavy lifting for communication. Once we got internet, a huge chunk communication was replaced by email etc. But, it also gave rise to eCommerce, on demand delivery services etc. And, the same postal services companies are doing better than ever before.

Because the population density was much lower back then.

How will we get our iPhone 17s?