May I ask why you avoided this? Often one of my favourite forms of haptic feedback.
The main reason is all combat would feel like a constant rumbling. Our intention is to bind vibrations towards receiving incoming fire and hitting the engines, so the player knows the ship is under stress. Adding weapon fire would be an overuse of this feature, and recognition between different occurrences in the heat of battle would become more challenging.
For example, firing a weapon at the same time damage is taken may lead the player to think they didn't take damage since it felt like it was just the weapon firing, leading to confusion when they discover half their hull is missing - or explode - in a way that feels unfair or random. We do not want this confusion to occur, so we chose the haptic feedback carefully.