What do you mean they didn’t?
Hatchets could have been used to butcher as long as I remember (since 0.8).
I do wish they’d be assigned the knife action, though. Otherwise, what’s the point of upgrading from a hammer? It’s not like they cover the function of two tools the way they are. I.e. you still need a knife.
Similarly, entrenching tools could benefit from “use_action: knife”, since they have cutting quality and no useful action.