When your hearthlings need to sleep they will search for a bed right? Well when they find one they keep it.
You can already just click on the bed, and use the “assign bed” button to tell the bed which hearthling can use it (or assign it as a “traveller bed” so that you can start getting travellers to visit your town.)
It’s a little more fiddly than having hearthlings automatically claim a bed for themselves, but it prevents 2 potentially annoying situations – one where the hearthling claims the “wrong” bed (e.g. let’s say your farms are all together on one side of town, but the hearthling claims a bed on the opposite side of town rather than one of the empty ones in a new building near the farms), and another where if you have more hearthlings than beds then you run into issues where hearthlings can’t share beds ever so you get hearthlings sleeping on the ground when there are empty beds.