I am posting this video by Keith Olberman as he stated it better than I ever could. As Keith asks in this comment, why does this matter to you? One of the most cherished phrases we have as Americans is from the Declaration of Independence "We hold these Truths to be self-evident, that all Men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness."
Religious groups, including the Mormon Church, spent millions to get this proposition on the ballot. One of the most awful things I saw was the day before the election. During one of the worst storms I can remember that early in November, standing on busy street corners throughout my town were dozens of children holding Yes on 8 signs. These religious groups used THEIR CHILDREN as props for their campaign of discrimination and hate. They used THEIR CHILDREN to propagate their religious agenda in a Country founded on separation of Church and State. As Christians and Americans you choose to discriminate, and fail to treat others as you would be treated. You fail to follow the teachings of the One you say died for your sins.
If the one you loved lay dying in a hospital, and the staff refused to let you be there for their final moments because "you weren't related", how would you feel?
If you had raised a child together and your significant other passed away and their relative took your child away because "you weren't related", how would you feel?
If the one you loved had been in a terrible accident and their parents wanted to keep him/her alive at any cost, and you knew that isn't what they wanted, but because "you weren't related" that left you with no recourse, how would their pain and suffering make you feel?
Now take those three questions and ask yourself - what if I lay dying and I couldn't see - touch - hold the one I love because some hospitals deny non-family visitation to the dying - what if in your last moments your were denied that comfort, how would you feel?
Marriage is not only for procreation. Marriage is not only a religious covenant. It is a promise, a vow, a commitment to share your trials and tribulations, your successes and failures, your happiness and sorrow with another human being, and if you get it right, it is until death do you part. It's fun and it's messy and it's jubilant and it's stressful and half the time it doesn't work. Most of us want to find that one person who makes us happy that we can wake up next to day after day without going nuts. In this day and age, that really is all that is anymore. For those that bring a higher calling to the altar, that is your prerogative.
Marriage is a social contract between two consenting adults establishing a legal union under the law. That really is all there should be to it. Beyond that, your ceremony is between you and your God, as it should be.