Someone somewhere else said that part of this is that women are no more than property of the men. So to them this is like nothing more than taking another piece of property from him / rendering it unusable. Like a fine. And the value of women is in their virginity until they're married so to take that is rendering some property worthless. And the effect on the women is not the point, not considered, sort of thing. It's not considered a punishment on them at all because they are non sentient objects.
But that's not right is it. If it were that, why does it need to be gang rape? Why do the women need to be paraded around naked? For that matter, if the elders have such power, they could just decree these women unmarriagable, or I don't know sundered or something, and that would do the job, and nobody would need to touch them.
So why does it need to be a gang rape? Why the humiliation? That is for the women, isn't it? Is it because if there's going to be an opportunity to rape then everyone who wants a go should be allowed?
It seems to me that this "punishment" for the man is a thinly veiled opportunity to really mistreat some women and have a thoroughly good time. IYSWIM.
But then, that's to me, all of this is so alien to me that I probably have zero chance of understanding their genuine motivations with this. I can't help but think that maybe they aren't entirely what they might say they are though.