We can face each other in our physical love and we offer each other our most vulnerable sides. We submit physically to each other and the submission is total, and there is no better way translate a loving of the soul into a physical process. So if sex is such a gift to each other, because the submission to each other is such a gift, then virginity must be even moreso. It was only fitting that the mother of Christ totally submit, on behalf of all of us, to her special role. The beauty of using a virgin to give us a Redeemer is missed unless one thinks about the concept of virginity as it relates to the rest of us.
Virginity is indeed valuable.
And it is not sacred because of this particular commandment or that particular rule of morality. It is sacred because totally submitting yourself to another is the greatest gift one can give. God did it for us. He showed us His soft side, so to speak, and continues to do it with the teachings of Christ and the Beatitudes. It's not corny to do it for ourselves, too.