I dont even think that it is a nerf.
I've always been a mid-close range archer with lots of Wpf and I only aim at the head. For me, it's not a nerf at all, it's just a new way of calculating things so my aim and my skill is rewarded.
It's way harder to rack up kills as an archer now, and I think it's ok like that. I have to take my time and focus on an ennemy to hit his head, I can no longer just quick-shot in a big group and hoping to get a kill.
Even more cool, It's now easy to help an ally in a close range fight without having the fear of killing my friend if I miss.
The big difference i've seen is against horses, does the hs dmg is increased on horses head? If it is, it's cool, I can be even more effective taking down the cav.
To conclude; yeah it's harder to get a high score, even harder to save myself when i'm being chased but this new system reward skill rather than luck so overall it's a good change, not a nerf.
(i'm an agy based archer with a horn bow, so I have the opportynity to take my time or even miss a shot, a str based archer would probably not think like me...)