It is not a comment of the dev's goals. It is a comment of the players position. If the player wants to succeed at something that has a negative then they need to adjust it by ethier buffing thier ability or reducing the difficulty(in the case of an attack debuff the enemy or flanking/rear attack).
If it is over 100% then that is how much they could safetly lose without actually having a chance to fail or how much they would have to impeed the enemy before they would have a chance to fail.