I still remember buying stuff from neutral factions in E:WOM. It will be good to see their return at some point.
If base movement values were higher, I could see moving into a city to conduct trade, but as it stands, just moving into the ZOC is fine, and doesn't slow down the pace of the game unnecessarily.
Just think of it as servants running to and from the city running errands for you, and you'll be fine.