The option to choose how many coins to spend at a time when buying curios, etc from Xur. It's really tedious to have to spend a coin at a time for ammo packs, especially if you have more than 100 or even 200 that you want to spend on ammo packs. Like in games such as Final Fantasy or Ni No Kuni, where you can say choose to spend 200 coins instead of 1, and you get 200 of that item (assuming it cost 1).