What was actually wrong with the way it was before AoW 3? While you could take a town, it wouldn't just bow to the conqueror; if they were too weak for the respective town size, the town would spawn a rebel force (which we have in AoW 3, when happiniess is in the red). So while minimal forces COULD disrupt things, they couldn't HOLD/convert a town (while in AoW 3 you can take a town with a Skeleton, then disband it and still control the town).
That worked KIND OF like an automatic garrison as well.
That worked KIND OF like an automatic garrison as well.