I think the main problem here is the hit arc that was introduced in A18. Considering you "missed" with the crosshair on the zombie, but the swing goes along. When will you know if you fully missed or if you partially hit (not with crosshair)? Only when the animation is finished, because the swing had to finish right?
Sure you could make the calculations at the moment of swinging and choose a specific animation if you hit, part-hit or miss, but it doesn't work like that. You hit the target when the animation is at a specific moment, not when you clicked the mouse button. It is a fraction of a second later, not instantly, so you could even start swinging, but end up missing if you moved your mouse from the zombie. On the other hand, if you start swinging when not looking even at an enemy, but turn so fast that you hit it (before the attack lands) then it surely counts.
In conclusion, you know you hit your enemy fully/partially or missed only after the animation is finished (the full swing is done), so you can't determine the type of animation beforehand.
I wouldn't mind more animations for swings, even diverse ones, but this would require simply different attacks for same weapons with varied attack arcs perhaps. Something like in many action games, where you have consecutive attacks when attacking constantly or after short periods of time (Attack, pause, attack, pause - like in Darksiders for example). Even if we'll have only one attack animation or only one set, i'm sure it'll be fine either way.