Certainly it's unique when compared to a simple superior-subject relationship. So, then, it's possible that arguments from superior-subject regarding the licitness of corporal punishment do not apply to this unique situation because there's something special about this relationship that would rule it out. I argue that physical punishment is particularly (and inherently) degrading and therefore incompatible with honor.
It may be true that physical punishment is felt to be particularly degrading in our culture, but it was not seen this way for most of the history of Western civilization. One can see how drastic the shift in attitude has been by looking at penitential practices. For most of Christian history, self-flagellation and other forms of corporeal penance were seen as normal and even meritorious. They are now viewed with suspicion and considered problematic.
That's why it's so repugnant for a child to strike his parent, a mortal sin, (vs. just talking back or disobeying in a light matter) ... because it's extremely degrading to the parent and therefore incompatible with the honor. And, again, the only possible rebuttal to this is that there's something so different about honor to parents, compared to honor to wife, that makes it forbidden in the one case but permitted in the other. But I have yet to see a valid distinction which would bear this out.
The honour due to parents occurs within a superior-subject relationship in which the parents are the superior. It is always wrong for the subject to strike the superior. It is not possible to measure how much of the wrongness of a child striking a parent comes from it being a superior-subject relationship and how much of it is comes from being a violation of honour. We cannot separate out the element of honour to see what effect it might have in isolation.
The honour due to a wife is honour due to a subject which makes it vastly different from the honour due to a superior. It is certainly enough of a difference to account for a difference in the licitness of striking.
In Scripture, there is more emphasis on marriage being a superior-subject relationship than on the husband owing honour to his wife. There are around half a dozen passages concerning the former, while I can think of only one verse concerning the latter. It is not surprising that the superior-subject relationship is the aspect of marriage that dominates our understanding of it.
Let's pick our battles. How can we even win this battle if we haven't first established the superior-subject relationship ... which the modern world denies? Let's start there and put this question aside completely. There's no point to discussing it or promoting it.
I too would much rather establish the superior-subject relationship. It is a very important and generally misunderstood idea. I agree that it would be far more edifying to discuss than corporal punishment.
At any rate, I am planning to take a break from forums for Advent, so I won't be discussing anything for a while.