It has always been part of this game series. It is done to make RNG not as effective as it would be without it. And that is why they made perks or attachments to help with it. So if you want that accurate shot right after sprinting you have to use the right set up to do so.
Otherwise people would abuse the ability to RNG with perfect accuracy all the time which would give them too much of an advantage over anyone that tried standing still and firing while still using other perks to further their advantage. This way they have to make a trade off to some degree.
Great video and it's given me some ideas for class settup.
it does not really help answer the wtf moments, insta kill bull crap and here is why;
From I understand from the video, this delay is built into the game so the same delay would apply to everyone playing and it's not something linked to their connection etc so this delay affects everyone meaning we still have an even playing field.
If this delay was the main reason for the instakill/wtf moments then the only people who would be out gunning more times then not would be people who are using this setup on their gun.
from the killcams i can see what perks they are using and with the gun i would at least be able to see the laser sight. The only thing I would not be able to tell is if they are using the quick draw grip.
but even with that aside, I hardly ever get killed with anyone using this setup. unless most of the people I encounter are using dexterity with the QDG, but on average I think mybe a quater of the people I come across if not less use dexterity.