I think it would be useful to be able to designate stockpiles to a single villager. The use to this is that they could store little bits for themselves, such as a few berries, or maybe things related to the villagers personality. This could be used to add a little more life to the settlers, also making it so that they don’t have to just raid the main stockpile but instead stock-up when their personal one is running low. It could also add things like theft, hoarders, and minimalists… maybe? Just a thought.
Thanks to what @Geoffers747 said I also think this could be the purpose of chests if they aren’t just decorative.