It's a long-standing thing in game design to make whatever would be cool narration or personal color for most character types into abilities for one's favorite type. I see this in fantasy games especially. One of the character races is almost always clearly the author's special favorite and receives about 200% the rules-depth compared to the others, as well as being so specific in personality and color that it might as well be a single character.
I expect that for Apocalypse World, one way this might manifest is that it's overwhelmingly tempting to pack the Moves section for any character type that strikes one's fancy. As the person who just proposed an additional Move (as in, right on the sheet, not eventually-invented for advanced play) for the Faceless, I may be guilty of it myself.
But it seems to me an important feature of game design to stay on the near side of the divide between "simple + elegant = emergent in play" vs. "make sure anything that can happen or be said is there as a rules option." This is clearly a very difficult divide to negotiate in Apocalypse World because the rules and narrations are so menu oriented.
If it turned out in play that the effect and ensuing carnage in I'm Right Here emerged from existing rules, without it being used as a Move, then I'd argue strongly for not including it as a Move. I don't know the game well enough, not by miles, to predict either way. To me, though, it seems that Gore-fisted would emerge from the existing rules and would effectively be a narration for an already-existing going-forward bonus in the right circumstances.
It all comes down to play itself, for sure. Without play, I find myself making up more and more that a character type "can do," only because I want to enjoy doing that in play myself, and since I'm not doing it, the only way I can enjoy it is to put it down on paper. With play, though, I can find out whether the coolest stuff I want is actually there to be generated already through the simpler mechanics I already have.
What do you think?