I would suggest (or as feedback the following)
if you make difficulty levels (easy, normal, hard, veteran, extreme etc),
turn friendly fire OFF on easy/normal), but be able to turn it ON if they wish too.
otherwise, turn it on (prevent it from disabling it)
if you have 1 difficulty (normal/balanced experience), let them choose.
either from start, else from option (or 1 choice per saveslot?)
but if the choice are rather in your sight, and the game purpose if it fit or not.
if a party throw a power bom (target everyone (include allies), than be it.
but to use it wisely, it is best use if he is the only one alive (unless he get dmg as well).
it's your game, so you decide

suggestions/feedback/recommendations are just their
eye/point of view, but you can add or not if it's doable or fitable in your game
