Imagine letting passerbys enter your village and possibly even join it. Wouldn't that be rather novel?
As it is, taking on neighbors is an all or nothing gambit. Allowing someone into your city allows them to rape, pillage, and destroy wantonly the moment that they're past the walls. Adding in siege mechanics isn't going to solve this. This shouldn't be such an all or nothing gambit. We need to be able to trust other players without running an extensive background check on them. There need to be in-game mechanics put in place that allow players to live within the same vicinity and not only benefit each other but even allow them to trust each other. The last thing that this game needs is the inability to commit crime though. That'd be hamfisted, exploitable, and just plain against the core concept of the game. Instead, the mechanisms need to add difficulty and complication to the entire matter.
Before we can properly assign any sort of mechanic or value, we need to look at what products need to be protected and what protecting them does. First we have the production facilities: smelters, ovens, etc.. Without these, a player and potentially even a city is crippled. That said, by disallowing other players access to these, you cripple their ability to function. Second are gates, doors, chests, and keys. Loss of access to these leads to frustration and, frankly, annoying workarounds. There is nothing quite as lame as the current system of teleportation that all players are forced to partake in. Without that though, any newbie with a key dooms your entire city. Next, there is the actual good stores. This includes everything from metal to food and without access to these materials, most players have no reason to be within your walls anyway. These are the least valuable and most easily replaced items. Sure, it hurts if they go missing, but they were going to be used regardless. Finally, there is access to players. Letting someone beside your hearthfire is literally giving them control over whether you live or die. While you can recover if you are killed for a criminal act in this manner, it is still a painful blow and consumes much time and a lot of resources.
In order, that means our priorities are as follows:
1. Production facilities
2. Hearthfires
3. Gates
4. Actual goods
1. I propose that members of a village should not be permitted to destroy production facilities without special permission from the village lawspeaker or chief. This includes production facilities built by the player trying to destroy them. Instead, they should have an option to sabotage the facility. If a sabotaged facility is not specially detected and repaired, then it will be destroyed within 48 hours. Sabotage should not be a summonable offense and should be repairable if you have the sabotage scents. Village members who leave a village should still be unable to directly damage or destroy production facilities for 24 hours.
2. Hearthfires are unintuitive for new players and a deathtrap waiting to happen for criminals. In its current system, hearthvaults become the norm and the concept of having a traditional village is lost. Instead, raiders have a little 10x10 box of bricks. Hearthfires should be securable inside of traditional buildings and should only be summonable on contact rather than at a range. Houses should have a special room just for storing hearthfires. It is not a necessity to place a fire in there but once someone does, the area becomes only accessible to them until someone forces the door or destroys the house.
3. I'm sorry but gates and keys in their current form are stupid. They need to be abstracted and players need the ability to carry keys without them taking up a valuable inventory slot. Allow containers and gates to have owners based on who has a claim over them. Pclaim takes precedent over Vclaim. In the event of a Vclaim taking them, then the lawspeaker and chief have control over them. The owner can assign players by hearthsecret who can open and close the container/gate. If a player is killed or KO'd and they had access to the gate, a thief can pilfer their "key" to allow them easier ability to lockpick the gate. Lockpicking is another action that should remain subtle unless caught and takes 24 hours normally or 8 hours with a pilfered key. The thief does not need to be there the entire time and instead just needs to initiate the action. A container or door that has been picked cannot be closed or locked again until it is repaired; which takes 8 hours.
All doors, containers, and gates should have the capacity to have a lock assigned to them. There need to be automatic alarms that can close and lock gates, house doors, and containers connected to them and within their range if they can detect criminal activities. They should detect scents being left based on their quality and raise an alarm if they detect them within their radius. This allows players to have a secure city without needing to have it locked down constantly. Having some kind of defensive structure would also help in these instances. Now cities would not need to be closed and locked at all times and a forgetful night won't equate into losing everything.
4. The loss of actual goods is fine. A thief should be able to clear a cabinet of its goods in a swift action and skiddaddle. I think the system works fine for this in its current state.
This would permit denizens of a city to still cause havoc if they felt crossed without having to keep everything behind its own brickwall, while at the same time preventing an open and free city from being a stupid mistake.