Lord Brutus said:
It is still worth doing missions for your village to improve their relationship with you. At high levels they provide high level troops when you recruit from that village. I've gotten 8 Nord veterans at once from a village I owned. You can get 16 Nord warriors at other levels of relationship. So, build the mill and the outpost so you get extra time to respond if someone tries to loot your village.
This is the only real reason to help villages imo. I forgot this in my initial post, but still i say ignore prosperity, etc.
I cannot get behind what jacob says. A town with a full garrison (300) of a mid-tier ranged and low-to-mid tier infantry is more than capable of holding it with the player's involvement, and you will make a lot of profit, alot more than any village, even at the lowest prosperity. Not to mention so what if the town's garrison eats up all the income? The troops are there for you to take out or put in as you please. When you get your ass handed to you, go to your town, grab more troops, and get revenge. It's especially useful for taking over other towns and castles, because if you lost, you can just come back with a full troop at decent levels, and take it easily then, or hell just force them to surrender if their numbers are low enough.
A village though? No matter what, I'm telling you, some guy with -1 relation WILL raid it every single ******** chance they get. It's not worth trying to keep it's prosperity up, it's simply way too much of a hassle. Relations doh? Hire 10+ swadian knights for 10 denars each? **** yeah.
Also, villages affect tax inefficiency as well, JUST as much as towns and castles. often times, villages actually cost more under your control due to tax inefficiency.