>>713192415BBI appealed to people who autistically enjoy the combat mechanics, as the dungeon is basically just higher lvl fight after fight after fight with random loot rewards to keep you coming back.
However if you're someone who likes the concept of DD because it has that "fellowship of the ring" feeling were you form your own party in the safety of a medieval town and then set off out into the world on an adventure before returning at night under the stars and head to the tavern... yeah BBI didn't do much for these players. Sure its good for a run through, but it doesn't have the long term appeal for this part of the fanbase like it does for the combat autists.
That's why instead of a new area, I'd like an expansion that basically overhauls the base game. More enemy types, dynamic enemy spawns, let the enemies/creatures roam and interact more, redo the loot chests so it's a mix of fixed+random with exploration being generally more rewarding, give each vocation a couple more skills, and open up the blocked off doorways as a few high lvl dungeons. And of course add hard mode & NG+ scaling.