yes, speaking you as main zealot, so i understand you very well.
i just think it would be simply a small addition that rewards certain playstyles / making some weapons good with some slight stability and/or precision/reduction recoil due to crouching.
but in the end it wouldn’t really change anything to your current playstyle, if not adding a new addition that slightly make you more precise and/or stable, that could come handy in certain situation, where you may need for extra precision far away or simply even at short range tbh just for the extra precision, and a reward by crouching if doing so, adding more “in-depth” mechanics.
obviously it won’t change much anyway, because for how i think, it will be a small slight increase so that you don’t really have to spam crouch just to get the best out of it everytime, but just only situational, a thing that exist just to provide a benefit in doing so.
for example, with a bolter, it would make sense to me, if you would gain slightly some stability/precision/less recoil, because when crouched, supposedly, holding the bolter way more comfortablty than when standing. Making the bolter less janky with recoil if crouching, due to the weight distributed well when crouched. IRL too i’d crouch with a bolter to shoot more comfortably cause a stance that should give you some stability at least. 
(i know it may some sort of other problem due to how animation works but still)
but seems like if you either stand still or crouch, does not make any difference, which was something i was thinking, with such addition, could make darktide more interesting from that point of view, balance permitting, but i don’t think would be anything crazy.
another thing is, people dumping all mag of bolter when standing still/moving
and i wonder what if people were just crouching to get some slight increase in stability/less recoil, i think it would make gameplay more variant and people trying new ways to approach to the game. even on paper seems may be a buff, i think it woulnd’t be that crazy anyway. also because people would still play as they always did. it is just to have an interesting addition.
i usually crouch when dumping bolter mag to plague ogryn head, to be more precise because of certain angle.
also another thing, i know helbore lasgun it is so precise already, but i have seen many times people just crouching for the “cool factor” i know some talents gives you stacks when crouching, but wish there was something more about this. and also peeking to walls/objets etc, which seems to be a veteran thing only xD