The excitement of a wife vs wife fight is shared by both parties, meaning each couple believing to be superior to the other... and nothing better but to let the wives settle it out in a match.
Would it work the same if it were the husbands to tangle? I believe the answer is no, and name it, genetics, psychology, it's the unpredictable scenario of having the women to step ahead and put themselves in a physical contest with the inherent risk of loosing it.
More over, being defeated in front of the husband is bad, but loosing in front of the other wife husband is worse (depending on the way she got beaten by the winning wife) because the chance of emerging as the winner and stronger wife was taken by the other one...eventually conquering the attention of her own man!
Thus, the intensity of the match can be sensed in a rather genetic way closely linked to sexuality. Two fighting wives are first and most, women - competitive by nature, and willing to defeat the other wife. Making the looser understand who's the "queen" and gaining the right to have the other as a "slave".
Lots of different feelings make wife vs wife matches very very hot, leaving every participant - both wives and husbands - with a lot of reasons to talk from this unpredictable act of having two married woman fighting each other, so...despite the thrill of annoucing the winner, this hot topic comes from this genetic and psichological involvement of couples in a rather physical activity.