"Sexual themes" in those games seem to exist just for the gratification of the (het male) player, as evidenced by the people getting mad when a game desexualises its characters after release. I haven't played baldurs Gate but as far as I can tell nudity in the game isn't there just for the eyes of the player, it serves a purpose in-game and in-story. edit: and at times (like in the character creator) it's not sexual at all