I won't know who want Milk , but with Milk you can make some works !!
* Milk removes your potions, if you have Poison II , the Milk can remove your potion , all potions, include Invisibility, Night Vision , etc.
* The Milk can be used as a clear potion.. The milk are not food and hunger bar will be fueled with +0 , i have 3 Hunger Bars, i drink Milk and nothing has been changed.
* The Milk are not useless, on battle with The Wither. But you need actually this command for battle with Wither: /give @p golden_apple 1 1 (0 reffers to regular golden apple , 1 will refers at enchanted golden apple)