Cut Throat is meh. Unless it has been changed recently, the attack will always be 25 AP. Even when your regular knife attacks reach 5 AP or 6 AP costs, it'll still be 25 AP. It's alright for midgame bosses tho I'd drop it tho.
It is better than you are making it out to be.
- it BTFOs bosses (took care of Zaman, Rathound King and Balor for me),
- it destroys all humans in the Arena (OK, maybe we can count them too for bosses),
- it is great against hunchback mutants,
- in any case against big groups you can throw a flashbang, tase whoever resists, cut the throat of whoever has the most HP, and then you have another 2 rounds (3 incl. the stasis round) to kill whatever is left. This is not as strong later when your attacks cost 5 AP, but that's lvl26.
- Against 2 enemies, you cut one throat, you tase the other, and they are toast. In this respect it is like Dirty Kick, only better and more fun.
- It synergizes with Cheap Shots incapacitation,
- it produces knife-unique gameplay.
So while you are correct that it loses power in the late game due to the AP cost, it does its job. But the most important thing for me is that it produces knife-unique gameplay. You are playing knives, you might as well play them like knives. When in Rome, go see the Pope!