i wonder why. perhaps they just want to have more of this stat and see how people play with it, so while it seams a failure in flavour to not have headshot booster ->headhunter, perhaps its just a test thing and it will be the other way around afterwards.
velocity feels good to land hs. if i click head i want to get head effect more reliably. could also be in crippling headshot why not? perhaps velocity into crippling and booster into headhunter down the line