One of the problems I could see with this, with the current way the map is done, is that all the maps that I have seen so far are relatively small. So travel between locations tends to go by pretty quickly and there is not (yet?) an emphasis on the danger of travelling between places, outside of ambushes. Getting enough supplies to go from A to B seems to be more of matter of having enough money to buy supplies at the start and there’s not really a risk of running out midway. For these kinds of interactable sites to therefore be meaningful they’d have to make everything larger or ‘zoom in’ on the map, so to speak, with longer travel times and more space between places where you could put these things. This would also make cities more special and function a goal to reach, while making these kind of smaller locations more important, since you’d have to find ways to stock up while travelling from place to place. Otherwise the map would get cluttered fairly quickly and there would be no risk of running out of any kind of supplies.
I agree that something like this would be very cool, though. Having something like farms opens up some nice opportunities for the player to interact with the world in ways that fit the setting. I recall it being mentioned that stuff like looting and pillaging in combination with something like a reputation system is one of the non-critical ideas that they were thinking of implementing. So say that you are travelling and about to run out of food. There are no nearby cities or fortresses, so you decide to visit some farms. Do you then:
A – Trade them for supplies at inflated prices (these farmers can’t really afford to do away with their own food, since would they have already been forced to give part of it to whatever lords owns those lands – better make it worth their while). Maybe even hire a naïve farmhand?
B – Raid them. Take some food and money, with a slight risk triggering a battle and you taking a reputation hit. In the case of a battle being triggered, you could have the enemy surrender after a randomised number of militia are killed (depending how rugged these farmers are). If surrendering conditions are too complicated, you could have there be a risk of one of your bros sustaining an injury.
C – Kill ‘em all! Take all the food, money and other loot they have. Chance of triggering a battle with militia. No reputation hit because there is no-one left to tell anything (could have an alternative battle type where some opponents are trying to flee, so you have to kill them if you don’t want them to spread rumours). Does economic harm to the region depending on the number of farms, which could result in less supplies being available in the cities. The carnage attracts stuff like undead and beasts, which would then affect them in their own way (necromancers to raise the bodies, a pack of ghouls who grow stronger and more aggressive, etc). Could trigger events like a vengeful son hiring other mercenaries to hunt you down, if he managed to escape the battle.
It would make for a dynamic way of interacting with the world, without telling the player that what they’re doing is good or bad. Just have your actions have logical consequences. So razing a single farm wouldn’t do much, but doing it too often could result in a ghoul infestation. It would also reflect how mercenaries have a historical tendency of looting and pillaging when they don’t get paid in time.