This feature was pretty dumb in RO1 and needed a lot more work to be believable.
Problem is, once you've restricted the triggers to appropriate causes and probability, reworked the pickup system so that you don't have to fish around to actually pick something up, yet can't do it trivially on the fly either, and reworked the inventory and view model systems to support null weapons, then you've just sunk a lot of effort into something that will only rarely actually affect gameplay.
There's no shortage of better places to be putting that much work into.
if you shoot my arm, i garauntee i'll drop my weapon!
There's not much support for that. A typical meat wound to the arm still allows for continued operation of that arm, and the normal response to shock is to clench up, not to relax. That's where the phrase "death grip" comes from, after all. On the other hand, a direct bone hit with battle rifle caliber is such a disaster that use of that arm is the least of your concerns, but those aren't currently modeled in RO2.
Plus, you have more than one arm.
A hit to the weapon may damage the weapon (a whole new system by itself) but it's unlikely to cause a fumble. It's no more impulse than recoil is, after all, it's just at a weird angle at a surprising time. Close your eyes and have somebody whack your rifle with a rubber mallet and you'll get a decent impression (note: may not actually be a good idea
). Metal/wood fragments coming off the impact of the shot is a bigger worry.
