Whereas, by contrast, the absence of death is the unintended consequence of, say, a shooting or stabbing (in any vital area of the body).
We can't go easy on an attempted murdered just because, luckily, the victim didn't die.
We also can't go easy on someone who killed using a punch just because death was unintended; the fact is that the victim died, and the fact is that not all punches are the same. They vary in intensity and area of delivery. A punch which kills (directly) must be quite a wallop, backed by a lot of rage.
My understanding is that logically there's that basic framework of required specific intent, then there are a few crimes that allow prosecuting for negligence, then very few crimes with strict liability.
I'm originally not from US so I'm probably still getting used that the latter two categories are quite common in US law (and that strict liability is even possible).