Tittle: Should we add an auto battle
Maybe if you add it in such away that makes it a natural part of the game. For example
1) The witch functions as a merchant why not it make so that she also works as an enchantress/researxher for the character.
You would bring her a certain amount of a particular drop from a enemy and after x amount of days you visit her again hence you gain some knowledge that allows the character to easily defeat the enemy (unlocks auto battle feature for that particular enemy).
Auto-Battle should also come with drawbacks such as reduced health after successive battles and reduced loot