As it stands, exploring the entire dungeon usually ISN’T a choice. It’s something most players just do automatically. Players very rarely leave any stone unturned in a dungeon. That’s partly because the game has made the costs of turning over every stone really cheap and easy and partly because, in most dungeons, players can’t really see the path to their goal anyway. And if they can’t see where their goal is, they can’t divert resources from pursuing it.