So...as the title says, why don't we have flowing rivers? Whether they are fast white water rivers or very slow gently rivers, I really don't know why they aren't more common. The same applies for shallow creeks.

Lastly for the more still bodies of water, why aren't there swamps and lakes? At the very least, allow for the capability for them to be made on custom maps after the game is released. The reason I say this is because I don't really know if there would realistically be swamps in the area of Greece the game is portraying.