Because dex/pyros already are generic enough; you don't also need to wear the exact same armor as everyone else.
Because you really don't need 37 poise; 35 is fine.
Because listening to the constant jingle-jangle noise of chain armor for hours and hours on end is a great way to slowly lose your mind and go hollow.
Because the Witch Cloak looks awesome and covers up the crime against nature that is the Hollow Soldier Waistcloth.
Because you won't miss the 7 stamina.
Because that extra attunement slot is more useful than the ability to equip a Short Bow (which you could do anyway if you choose to be a heretic and sacrifice The Fashion).
