I'm not sure you can blame the Okinawans. I started with Goju Kai (Japanese) who taught the twisting motion. Changing to the Okinawan form of Goju gives you a 'neutral' fist which is not exactly vertical but where the fist is naturally positioned if you extend your arm out from carriage with your elbow pointing down.Your understanding is incorrect. The entire system of Isshin-Ryu uses no torquing punches - intentionally. The founder experimented with them briefly after being pressured by other masters on Okinawa, but returned to the fist formation and punching method he developed for his system. No one - and I mean no one - accuses Isshin-Ryu karateka of not punching hard.
And we can also throw a one-inch punch with great power. No torque required. The hip, the knees, the back, and the shoulders all contribute to good body mechanics, which increase leverage to deliver a powerful punch. Twisting the fist at the point of impact does not impart power to the forward momentum of the punch. A drill bit turning does not increase the downward pressure applied by the drill.
The only punch we throw in which the fist turns is the uppercut, and that is not a 'torque' but rather a block incorporated into a punch. Which you would know if you were familiar with Isshin-Ryu as you claimed.
Personally, I have taught Tate tsuki (vertical fist) all along and the one inch punch is also a staple of the Okinawans. The power of their short punches is hip generated like the WC punch that is often described. For me, the angle of the fist changes slightly depending on where the trajectory is taking it toward the target, if that makes sense. I was shown that in the small amount of Systema that I have trained.
My theory on the twist punch is that if you were using a one knuckle punch to the ribs, the twisting motion could give rib separation and greater damage.
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