This setting is vaguely medieval with occasional spots of lower/higher technological and cultural development. Still, contemporary underwear in the Realms feels anachronistic.
It does a bit but I recall a fresco from the Villa Romana Del Casale that shows females in (sort of) "Bra" and "undies" playing sport. So maybe the Sword Coast guild of under ware and ancillary appendages (presumably it exists) had similar thoughts. Wonder why it didn't catch on.... As for a nude mod, not my highest priority for the game but might install one in the future to add a bit more edge and interest.
