The fact that it's so complex and responsive to patient, fear-free stimulation and so easily hurt by the wrong kind of handling? Women's bodies can be played like violins by a skilled partner: we have clits, we're sexual from head to toe if properly caressed and there're the multiple orgasms. All this seems like a total evolutionary waste if Homo Sapiens have always primarily engaged in the rapey patriarchal model of sex.
Is it all just a carry-over from our bonobo DNA? Is it supposed to facilitate pair bonding (maybe the 2nd trimester horniness is part of this)? It also all seems really excessive if it was all just intended for making babies. Just musing here.