There is no point in arguing about money and the economy system in EB.
Its completly nonsense and is as far from reality as it goes, but thats because of the rome engine.
So the team wants the romans to have the ability to spam stack after stack just like they did in the punic wars and so the only way is to make their units cheap and their lands rich.
But I would wish for Multiplayer to have the romans cost more than they do now.