Because it'd be more complex and interesting and not just about optimizing to win.
No emergent gameplay at all in Civ.
No emergent gameplay at all in Civ.
Have you read about the Russian frontier? As soon as it was at least somewhat secure so living on it wasn't a sure-fire way of getting enslaved by Muslim steppe raiders(Tatars), the empty land was filled up by peasants looking for land to farm.
An increase in population led to more slave raids, so Moscow was forced to push the border further south to protect the farmers. In this way the border kept moving south. In 250 years, this mechanism caused the Russian state to expand from Moscow to Crimea.