I had read the views posted on Rediff relating to the subject by a user. I am in complete agreement with her views though that might amount to being branded as conservative or out of vogue.
I feel sex being a post marital activity and that too restricted to the wedding partner reflects a state of societal development. Humans before they attained their present state were also like any of the other creatures in matters of sex and life. But with our innate capability to think ahead and to evolve has what as resulted in our attaining the present ideology of sex.
Had it not been for this standard of development then we would be anything equivalent to the animals that we look down upon. Also, the society as it grew has thrown up a different sect of people who have pleasure giving as their profession. Where all people end up doing the same then sex would end up being more of a gratification and profession than of a pleasure and satisfaction.
Also, the Indian mythology attaches a very important place to sex in its own style. Any worldly person is not deemed complete until he copulates and bears off springs and this contributes in a way to his salvation. So it not just for sex!