Are the knuckles really supposed to kill the zombies in 1 punch?

I'm on my 2nd Nightmare playthrough (the first was survival), and I can pretty much get through the rest of the game just punching the zombies to death, as they're getting "gibbed" with the 1 punch.

So I thought "hmm, I guess I'll go to akumu" and it turns out I can't move up to that in-game. So... what is the point of any ammo at all with these knuckles and what is the point of even giving me a playthrough with them? Hmm?

Myabe to make up for the utterly useless Rocket launcher? This game seriously needs a patch to fix this stuff.

Well surely the point of the knuckles is to:

A) play a new game punching the crap out of everything that moves

And

getting rid of all the frustration and anxiety from the playthrough that gave you the knuckles in the first place

And .... hopefully ...

C) for console users and trophy/achievement hunters ... the "finish the game in 5 hours" deal

... at least .... that's what I'm hoping for...haha

How lame.

I won't be finishing this playthrough, I hope the DLC comes out soon.