Historically, this doesn't seem to be true.

Villages appear long before defensive fortifications in the record, in many cases. Pure reason is not very good at forming predictive theories about history, as a general rule.

There are many possible reasons for villages, and cultural reasons are a very big determinant of how people live. So are economic reasons. Many of us live in big cities now, and it's generally less safe.

You get villages because foraging really sucks. It's an ease-of-survival thing around food production.

Foraging is done from villages as well. They tend to not have tents/houses, just a community fire that moves when the tribe moves. Still a village.

Foraging sucks less than subsistence farming. However farmers are able to put a lot more people into given land area and so farming villages won out.

Just having a number of people living together is protection even before fortification. Your point is well taken though.

Don't underestimate just how many people are needed to defend a village.

A village has a lot of land to defend and not many people to do it. The local town or city sized group will just pitch up with many more men and overrun you. All whilst having enough people left for defence. And they are likely to have more access to heavy weapons that can blow your house up from a distance.

Nations will overrun villages, but a city alone doesn't. Cities need villages to provide food, so a city never goes to war - it is instead the nation, headed by the city but also including all the villages.