There's no reason for a new player to enter a dungeon if they don't know what their role in a party is and how to perform it at an adequate level, they're supposed to be done before you enter your first dungeon anyway so I don't see the problem with making them required.

I know the story already directs you to the Hall of the Novice but it doesn't explicitly tell you to actually go in and do the lessons, so a new player (who might even be skipping dialog and not know what they're doing there in the first place) might have no idea what to do there and be on their way.