I've noticed a few people asking why are defenses relevant if nobody can attack us?
Why build walls at all?
For the after the prelude? That will take to long, I'll get bored.
So my thoughts are horde waves every few days that just attack our zones and settlements, possible stealing our supplies if they break through. Could also be reason to team up with your fellow man.
I mean how awesome would it be during these times Good and Evil tribes teamed up to fight side by side all for the sake of survival? It would also make walls relevant (which make masonry and woodworking useful). At least then people wouldn't get bored waiting for tribal warfare and give us a reason to team up for survival (not just for building).
I know this is a sandbox and we make our own enemies but the world is our enemy as well. World events such as natural disasters and NPC hordes would bring us together even if only for a short while and give many settlements a purpose.