*bursts in on unrelated tangent*
Alright, I think I've figured something out!
The reason why town residents in Terraria and so far in Dragon Quest Builders don't feel much like accomplishments but followers in Skyrim do has to do with linear progression. It's directly tied to how people complain that trophies/achievements related to gameplay progression feel "cheap" because it's the same thing!
Of course, that's not the only factor as to why Followers in Skyrim feel better, because they also have character arcs or at bare minimum explainations as to why they're there. That's the key, though. Nonlinear effort (I.E. player is not railroaded into obtaining character) + feeling of attachment (I.E. character has unique, likeable design and empathy inducing backstory) = satisfaction.
Naturally the same also applies to pets and homes, and possibly other game details pending further examination.
I'm not trying to come up with some "ultimate breadwinning game design," mind you, just gradually cracking open an epiphany on what details I particularly enjoy in games and what could improve them further.