Personally, I'm really not a fan of most "park a merchant in front of a dungeon" implementations. In gameplay terms, it makes sense, especially when there's really no justification for a full town at that point in the game. But in terms of internal logic, it usually comes off as an extremely half-assed way of shoring up that section of the game, since it usually just doesn't make sense under even the most cursory examination for the merchants to be where the player needs them.
Since I'm involved in the writing for this game, I'll be trying to ensure that any oddly placed vendors in the game come off as more than conspicuous patches.