The stud and regulator pin system used in the 7S26B is very similar to the Etachron system, used in most common ETA calibers for years now (which can also be much more easily adjusted than traditional regulator systems- a marked advantage of the 7S26B). You can see the same thing happen with these ETA calibers, but I do not fault the manufacturer so much as the user (in either case). The amount of force necessary to shift the body of the hairspring enough so that it will catch on the outside of the regulator pins is truly great, and while I don't doubt that you have had your fair share of headaches because of it, I don't know if decrying Seiko openly in public is warranted (I remember you mentioning this a few months ago, too). I'd tend to decry those owners who subjected their timepiece to such treatment.
There is a safeguard designed into the regulator pin design in the 7S26B to avoid the reg. sweep of the hairspring (the outer most portion of the hairspring that goes in between the reg. pins) from jumping out of place (and also the body jumping into the reg pins when a shock is delivered)- notice the small perpendicular tips at the end of the reg pins:
The reg. pins are designed to be rotated in order to minimize the amount of play the hairspring has between them, which is key in obtaining the best possible timekeeping throughout the largest range of amplitude and positions. Here the pins at their fully widest rotation, allowing one to remove the balance and hairspring (not centered between the pins in this photo by the way) from the balance bridge if necessary:
You can imagine that in this position of fully open, it might be easy for the body of the hairspring to be caught in between the reg pins if a large shock in the correct orientation is received, but look at what happens when the pins are rotated to a more normal position, where they are almost pinching the reg sweep of the hairspring, but not quite (just a little breathing room):
It should now be much harder for the body of the hairspring to jump into the slot, because now the slot is not parallel to the hairspring- in fact I cannot really imagine the body being caught in this slot if the pins are properly closed- is it possible that the body of the spring is catching all the way on the outside of the reg pins in the cases you have seen? Have you noticed how closed the pins are rotated in these cases? If not closed enough, then I certainly could see the body getting caught in the slot- with a shock. As you can see here- that is a phenomenal amount of movement by the hairspring body- and would thusly be caused by a phenomenal amount of shock:
Again, I don't deny your problem, Rob, and while I sympathize (a lot of my day is spent undoing the actions of others against their timepeices), I don't know that Seiko should be receiving full blame for a faulty design or materials. The hairspring has to be a certain size and thickness to allow the watch to run properly, and a side-effect of this is that a massive shock to the watch can cause the hairspring to be shifted outside of it's normal oscillations. I don't think this makes the watch any less robust than it should be, if you want a watch that you can throw against a wall, buy a tennis ball, you have no place owning a timepiece, that's what I always say