So, to start it off, I don't think EVERY village needs to be unique or have complexities. I think the current trait/personality module is a pretty good step for that!
I think it'd be nice though if littered amongst the common run ins are a few villagers with like a more detailed development that sets them apart, I think more similarly to NPCs in Animal Crossing or Skyrim, where players would go out of their way to try to recruit their favorites.
A few suggestions would be:
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Maybe there's an NPC who's a toy maker that you can recruit to your village and dependent on his happiness percent they'll give you random toys or something they've been working on.
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A really skilled hunter who's obsessed with alcohol and is always drunkenly walking around the village or something (Maybe even a side quest where you help them sober up because they want to be a better more clear minded help to the village if when their percentage goes up a certain amount.)
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An academic NPC who enjoys the study of a specific trade, maybe even gifts books that you can store away and read as later heirs to boost skillsets. (Or maybe something like a quest bringing them things specific to the trade, and then wait a season or 2 for them to log their journals.)
And sometimes perhaps maybe at the end of the season these specific NPCs can trigger events. That can make or break their continued loyalty to the village.