I think it would've been an interesting approach, too. Economic warfare alongside ray guns and battleships, but it probably wouldn't have been fun for the audience. The writers may have gotten bogged down in the details, too. We know Klingons use something for currency - darseks, I think. The Cardassians use leks, I think. Don't know about the Romulans.
Give financial warfare over the holodeckgone wild episodes anytime.