I think people confuse "marriage" with a "wedding." A wedding is the ceremony celebrating the union of two people in marriage. You don't need a wedding to create a marriage.
It is we who create the sacred. When we say, "Marriage is sacred," we are reminding ourselves that marriage is more than just a contract; more than a tax benefit; more than a way to pass property between two people. Marriage is a work of art that two people spend the rest of their lives creating. When you make decisions, you no longer simply take yourself into consideration. You take into account you, your spouse and your marriage: the holy trinity.
Marriage is not for everyone and that's okay. But for those who find someone with whom they can create something sacred, it's a wonderful experience.