The simple explanation is that women who have orgasms will enjoy sex more than ones who don't. The more you enjoy sex, the more sex you have, and the more sex you have, the more you reproduce.
Except that if this purely adaptive explanation were true, then there would be greater evidence of it being selected for. The study shows only a 60% genetic component to female orgasm. If it were as straight forward as you suggest, then I would expect that number to be in the high 90%s.
The biggest mistake in the purely adaptive explanation is that for human females, lasting reproductive success does not come with having the most sex, but with the quality of the mate with whom you choose to reproduce. Because of the huge investment in child rearing among humans, the females' reproductive strategy isn't advanced by having more sex, because biologically, females are quite limited in the sheer number of children they can have during their lifetime. So females cannot appreciably increase their reproductive success by increasing the amount of sex they have. (Assuming that they are not starting from "zero", of course.) Males, by contrast, have no such biological constraint. A single high-status man fathering hundreds of children in a single year is easy to contemplate. It would be impossible for a woman to come anywhere near even 5% of that number.
A woman's reproductive strategy is maximized by being able to attract and choose to mate with high-status males and to find males with the ability to help raise children. The net result is that following this strategy she will have more offspring survive to maturity; her sons will have a genetically better opportunity to be high-status males themselves (with the opportunity for high reproductive success) and her daughters will have a genetically better chance of being able to identify and attract high-status males herself.
I mean, would men want sex as much as they do now if they couldn't have orgasms? I think not . . . .
Because this goes to the male reproductive strategy. My "explanation" acknowledges that the male orgasm is adaptive; that is, that it exists because it was selected for by evolution. Female reproductive strategies and male reproductive strategies differ significantly.
The "better sex = more sex = more reproduction" paradigm is the basis for the selective pressure in males but, of course, doesn't take into account social groupings, the differential rates of offspring survival, etc., and the effects these have on reproductive success. The female reproductive picture is different.
"The" female reproductive strategy? Like there's only one? Which mysteriously is just like 20th century American traditional female reproductive strategy? "Marry a high status male, don't waste your sexual prime on that hot guy just because he's cute."
One word - bonobos (a subspecies of chimpanzee). One of the few species that we know has sex just for fun.
Female bonobos don't go looking for "high status males" to reproduce with. They have sex with lots of males, all of which give them presents and help raise the babies. Bonobos don't worry about which guy has the coolest car and which one is going to buy them the biggest dishwasher and which one is going to help put the kids through college.
Back when human beings evolved, they didn't worry about cars and dishwashers and college tuition, either.
Imagine if human females liked to have sex with a lot of males (no!), and nobody knew for sure who the father was (double no!). She'd probably have the most sex with the hottest guys, but "marry" the guy who would make the best husband and/or father.
Best of all possible worlds, no?
Meanwhile, the guy who is worried that he's going to be stuck raising someone else's kid would rather marry a lady who hates sex, because she's more likely to stay "pure." That's why a lot of cultures cut off women's clitorises or sew their vaginas shut or lock them in harems. Unrestrained female sexuality is dangerous to the guy whose only lure for women is dishwashers and cars and college tuition -- in other words, material goodies, or what you call "high status."
So, the ability to have an orgasm gets the hot ladies into bed at an earlier age, and keeps them looking for hot sex their whole lives.
Maybe they can't have several hundred kids, but neither can the bald-headed pot-bellied dork males, and neither can the non-orgasmic females. So just one or two more children over a few million years means they're reproducing sooner, more, and later than the non-orgasmic females.
Case closed.