Sex in an Ideal Society
Eventually, technological advances may make human biology irrelevant, but until then, sex as we know it will play an important role. Here is my vision of its role. The role represents both freedom and restraint.
On the one hand, sex is practiced openly, publicly, and casually. Sex is guilt-free. Most people are not shy about soliciting strangers for sex. Exchange of sex for money or favors is generally accepted. The right of everyone to have sex is respected both by law and private parties. Among other things, parents do not prevent children from having sex. A spouse does not get mad when the husband or wife has some casual extramarital sex. Sexual images are uncensored.
On the other hand, a majority are in (mostly) monogamous relationships. The family as we know it continues to be important. Sex is practiced in moderation, with people confident in declining it. The right to privacy and individual objections to sex and even (to a reasonable extent) sexual images are respected. Generally, no money is exchanged for sex--sex is generally enjoyable to both/all participants.
While humans will eventually transcend biological bodies, sex-like experiences will likely remain because of their emotional value. Future technology will overcome the limitations of wrong gender and of physical ugliness that currently prevent people from enjoying sex with each other.