We need to hear those vows. Those words become tangible to the other person. There is a security that someone is willing to be by your side through whatever comes your way.Been there done that. Both living together with one and getting married to another. They are TOTALLY different situations. I understand what you're saying, ClayT.
But...
Id never recommend anyone live together thinking there is a true commitment. It may seem so, but its not. That piece of paper and those vows REALLY solidify commitment, for most people anyway. I also agree with what Hobbit said.
Getting married is BIG business. The average wedding now cost 24-28 thousand dollars. With gifts included, approx 72 billion dollars are spent on weddings annually. Those of us who conduct the ceremony are the least paid of all.
I recently was in contact with a bride who is planning a rather large wedding; 300 guests, renting the Hall of Mirrors for her reception. Said she didn't want to pay over $200 for the person who marries her. She wanted to "concentrate on the important stuff, like the cake & her dress." These 'girls' don't realize that they can get married without a cake or a dress. They cannot get married without someone that's legal to prounouce them husband & wife. They need to get some of their priorities straight. They get too caught up in the planning; more thought needs to be put on the marriage.
There are also a few drawbacks to this living together thing. Couples who just live together to "see if they are compatible" usually don't make it to the altar. Seems the couple needs that commitment in place, the betrothal, in order for it to actually come to fruition.