I disagree with some posters here. With cottage heavy Econ, I usually convert my gp farm to merchants after education. Cost isn't a concern with Org Rel whipping. Come banking, even a mediocre city can produce a lot of gold running 4 merchants and remaining pop on hammer tiles building wealth. Had one game with a few mediocre cities doing this and I was running 90% with surplus gold and no holy city shrine to speak of.
Additionally not all games are all war. If every game is spam units, conquer, build wealth in newly captured city it would get pretty old pretty quickly, no? Well, at least for me it would.