So let me get this straight: For all you know, the region is permanently lost to a dark, impenetrable cloud of poisonous fog, almost everyone there is dead or worse, and you get neither gold nor food nor even reports from it anymore...
...and your complaint is that the Daimons never sent someone there with a flag to plant on top of the city gate?
But I did get some reports. Most importantly, though, I had the title of lord (giving me voting rights in our political system) and duke (giving me feudal rights over lordships). The region producing no income was an inconvenient, sure, but still. I was getting reports, and then all of a sudden I'm not lord with no notices about it.
Well, he does torture everyone he gets his hands on, and IC some people believe that he uses the fear of his victims for some sort of sinister arcane purpose. If it's fear he feeds on, killing people would be counter-productive, wouldn't it?
Either way, considering how upset some people (Chenier) got over the mortality experiment in the last Invasion, I think it's just as well that Overlord isn't devouring every character he gets his hands on. I know I would be a bit unhappy if my non-hero character got killed because I got unlucky enough to get captured in a battle. He's one of my oldest characters, and I'm far from done having fun with him.
I'd be ready to accept mortality back when things get hopeless. Right now, they are just bleak. Imo, mortality should follow despair, not cause it. It should only come when it is blatantly obvious that BT is lost and that we are fighting the last few final battles.