Of course this isn't surprising. What is surprising is that any woman is capable of orgasm, since a woman's ability to orgasm is completely unrelated to her ability to produce off spring.
There is a debate on possible purpose of the female orgasm http://www.popsci.com/science/article/2011-09/what-point-female-orgasm
The purpose of the female orgasm is to give the female a reason to seek males, especially now that the need for males to provide and protect is greatly diminished. If female orgasm disappeared tomorrow the population would steeply decline.
you mean, some people might have sex for... fun? :O