Hmm. I was very anti-marriage until I got married.
As a teenager I thought most of the marriages in my surroundings made very little sense, and I did not see any reason to get married myself. The ceremony means nothing to me, and I don't think a relationship gains any sort of validity by purchasing an expensive party and a piece of paper.
But when I had been with my partner for seven years and I was expecting his baby, and he proposed to me - I just couldn't think of a good reason to say no either. It made legal issues related to parenthood easier, and it WAS a beautiful ceremony. The vicar was an old friend of our family, and he said at the altar that we were really just making public what we had already had between us for seven years.
I still don't see any general reason to get married. It did not alter my attitude to my partner. Well, there is a semiotic reason I suppose, if you are English speaking: "Boyfriend / girlfriend" sounds sort of ridiculous after some years, and "partner" sounds a bit same-gendered. In Danish we say "kæreste" meaning "beloved", and I still call my partner that, rather than "husband".
What I don't get at all is people getting married several times. Monogamy is not for everyone, and I am fine with that, as long as they are honest about it - people are different after all. But if you want to keep shopping around for relationships, or want the liberty to give in to biological impulse, then marriage is totally out of place in my view. In our culture there is nobody forcing you into it, after all.