@finland it's possible to balance it if you put a cap in it too how much npc's you can hire.
Take WvW in gw2 for example. A solo player can destroy a tier0 supply camp. But at tier 2-3 it's almost impossible. Same idea can be applied to settlements here.
Maybe have different type dungeons or raid bosses in the different worlds. Instant on one world, open dungeon on another and maybe open world bosses on the human world.
@daz and while hugging a random farm animal 
Btw, if I'm a fire demon, can I have some of that immunity fire elementals get?
Funcom did the ingame pubs/taverns really well. Drunken brawls and I never forget the drunken piss command. That was sadly removed when someone reported to a GM that he was stuck near a tavern. GM tried everything and finally showed up with a char at the player, only to be pissed on by a group of players there
It's the 3 worlds with 3 rulesets plus you explore instead of grinding mobs. The big problem with AO online was it had a heavy grind and the best grindspots where on 24/7 lockdown by big guilds. And I was in one of those guilds and the grind groups had a preffered max number for best xp/hour. So if that number was reached you where left out. Was really frustrating.
You can be a dictator! The absolute ruler of your domain!
I would like to place barbed wire around my guild settlement