Imo needing to go to the bank would add vastly more annoyance than benefits (immersion, realistic economy, proper value of items). It'd be a mechanic that purely wastes time and thus should be included automatically as QoL. Exchanging money at merchants...I guess it wastes less time, but it still wastes time.
If there wouldn't be automatic conversion then I'd much prefer BG3 just stick with a single currency.
Regardless of how they handle the implementation of silver and copper, the prices need to reflect what they actually represent. A set of Studded Leather armor costs 45gp in the tabletop game. I fail to see the reason why it costs ~1300gp in BG3. Furthermore, I reiterate, if a player doesn't feel like making a manual conversion to gold, they could easily pay in silver or copper.
