"correct this"?! Do you honestly think that BI is unaware that the weapons like the mini-gun fires slower than their real life counterparts. This is purely done for optimizations sake.

While i agree the cannon on the heli should produce shake, i don't believe the rocket prods should produce anywhere as much shake, you can see that in the video as well.
I can't really say how much shake, if any, is produced when firing the cannon. At the same time i think the large amount of shake in the video is due to the strong zoom that is seen.
+1

AFAIK physx effects as shown in the planetside video can be handled by the GPU on nividia cards, while it can only be handled by the CPU on other brands like AMD. This creates a problem since ARMA 3 is already very CPU intensive as it is. If ai and complex physx effects has to be run on the CPU it will most likely result in severely lowered frame-rate.

And i strongly disagree with Raoul on the claims that the UE3 engine is more demanding than the ARMA 3 engine, i have linked min and recommended specs:
UE3: https://udn.epicgames.com/Three/UE3MinSpecs.html
ARMA3: http://www.arma3.com/buy#requirements

Although this would be a nice feature(i play planetside with the effects on), i don't think it would be wise to divert resources from developing other assets or features, furthermore i don't think its a realistic goal to overhaul the effect system that is already in game this far into development.

+1

Voted up, it would be a nice feature to see :)

How would this add any value to the game, besides it being realistic?

This is present in a other games, problem is that in arma your head is closer to the ground.