Only because you crave the feeling of being desired. You mean their are people that DON"T crave this. That would be pretty strange behavior.
If you didn't, then having connected sex with a woman who fully occupies her sexuality would still be one of the easiest ways to get an incredibly wonderful feeling, but it wouldn't be the end-all-be-all your mind is making it out to be. How could a woman possibly be fully into her sexuality WITHOUT desiring sex?
You'd then be open to dozens of other ways to make yourself happy. You'd be well on your way to becoming a man who possesses himself and that feels significantly better than the greatest sex in the world. Can you give an example from your life. What is out there that TOPS passionate sex with a desirous woman. How do you get your body to replicate ALL the sensations of passion?