I could definitely see this. Though this brings up a lot of questions thus asking how these places were to be arranged. I would assume military protection would produce some sort of economy as they would provide protection though not housing unless there are chances to become BoS paladins, NCR rangers, Enclave Commandos, etc for the PC.
I think player created and run towns should have some sort of military protection with military bases at Hoover Dam, Windfarms, and various other places. In addition to this, outside of towns there could be camps along roads entering the area or near it, if there are no roads. So each passage/road will have an encampment as a precautionary lookout. If these fall, the town would be considered under siege as it would stop fast travel and force those in the town to fight or surrender the control over to the faction that has engaged with the city. This could prove to be an awesome system of dynamic change within the fallout world. This could also apply to strategic points that would be militarily important as opposed to economically viable. Obviously, one may attract the other but I don't think people should be able to build bases as you may end up with a carve up that will end in a stalemate between factions.
Lastly, this would apply for independent towns run by guilds can go one of two ways: faction allegiance gaining support from their resources OR mercenaries and contracts. The first one I believe I mentioned would include some sort of taxation whilst the latter would see all income pooled into a guild bank. The guild bank would then be able to tenure out contracts on defence (turrets/robot/mercs), 'hits' on trouble makers including individuals, guilds or factions even, or even structures such as walls.
Another note, will there be political dynamics such as Town Councils which are effectively a guild leader and officers or something like that?
