While I understand that as a gay man you find the vagina unappealing, I find it hardly correct to say that the shape and look of it is a mistake of nature.
The vagina serves the purpose it was created for. It receives a man's penis, and shortly after, receives his seed. After 9 months of the uterus nurturing the child, the child passes thru the vagina, thus making it "the gateway of life"......the gateway that all of us passed thru when we were born (except those born as C-section babies, of course).
The shape of it is a part of its function, for reproduction and for the woman's pleasure, and obviously the look of it doesn't hinder straight and bi guys from wanting it.
There is no mistake. God did a wonderful job when He made our bodies.