A cursory look at the design and anatomical positioning of the male and female sexual organs shows that when God designed homo sapiens, aestheticism and ease of access were not high on the job description.
To get past the cervix, climb up the uterine wall and find a Fallopian tube a sperm must be armed with the physiological equivalent of an oxyacetylene torch, a set of Alpine crampons, several large-scale Ordnance Survey maps and a gold American Express card. Once there, the chances of meeting a willing egg coming in the opposite direction, in the dark, are only around one percent.
Attitudes to sexual practices vary widely from culture to culture. Even something as innocuous as the kiss is not universally popular. The Inuit rub noses for fear of chapped lips, the Kwakiutl Indians suck each other''s tongues and the Sirionos of South America appear to lack any intermediate show of affection between wishing each other "Good evening" and the commencement of rutting.