A very good question, EZJ, and one that is near impossible to answer – though I will do my best to start us off.
When dissecting the appeal of a women's match, one of the key themes is the physique of the combatants. I'm drawn to the powerful portrayal of women - athletes, wrestlers, Lynda Carter, and so on. On the flip side, it may be good comedy, but I don't find it at all interesting when two obese women go at it. So the enjoyment of a woman's physique plays some role. And naturally, the concept of beauty can be quite broad for many of us. For instance, I enjoy the celebrity-beauty (Angelina Jolie), athlete-beauty (Monica Brant), and even bodybuilder-beauty (Denise Masino).
Another theme has to be the competition. One person will WIN this confrontation, while the other will LOSE. It is more natural for men to be competitive than women (I'm going out on a limb here) and that's probably why you see more men interested in sporting events than women.
I'll add more to this discussion after I've thought it through more carefully. Maybe even do some research! I'm curious to hear what other FWF fanatics think of this subject.