My response is not an argument as your comment may be true for your system.
I don't like the baseball bat analogy because it's not a punch. The mechanics are not the same. Let's put the baseball analogy in the context of fighting.
Guy with baseball bat swings through as you stated. Watch what happens. He did exactly what you said. He swung through with power. If he hits, then great. If he misses then that power carries his swing through and as a result he gets punch through the opening caused by swinging through beyond where he actually needed to swing through. This is why many practical staff forms do not have staff swings that swing through like a bat. For the one's that do swing through like a bat, those swing around back to the beginning.
You can see my swing through punch here. You can also see me do multiple swings, and you'll see me do one that is like your baseball bat analogy except for the fact that I do something that covers that opening caused by the baseball bat analogy. I know from first hand experience because I got kicked by a Sifu who was helping me with my Jow Ga Kup Choys to understand the opening that swinging through leaves me, which in turn made me understand completely why this particular punch is always done a certain way in the Jow Ga form. You can also see the other things that were mention about the Paau Choih.
It was stated that the punch required a set up, but I think that's because of how Lama Pai throws them (You will have to ask them or if you take Lama Pai yourself then you would be able to compare the difference). In Jow Ga, the way that we throw the Paau Choih allows me to use them as an initial attack that doesn't require a set up. In the video my initial swings are not thrown short they are attacking the guard. I continue the swinging so I can keep him at bay and reset.
You can also see the punch here from this other Jow Ga School in Australia.
When I do some of my big punches, it is less about punching through the target (because punching through on a circular punch is only within a small range of contact), and more about following through, so that I can use the momentum of one punch to drive the power of my next punch. This not only makes my long fist punches faster, but it's also faster to do, than trying to reset that type of punch pull it back to reload and then launch it again. It's like you stated "it's an all or nothing" technique. You don't want to bail out of it. The effort that it would take to actually slow some of the long fist punches down from full force to stop makes bailing out very dangerous.
I also agree with your other statements about being difficult to spar with some of these techniques. This is why the punches in my sparring video are slow in comparison to how they would actually be thrown in a real fight or even a competitive fight. Here the baseball analogy fits. It's like swinging a baseball bat as hard as you can and then trying to stop your swing so you don't hit the ball.