I think I could have lived my whole life without getting married. To be honest, the reason we did was in a big part for legal reasons of immigration and residency.
However, I think it's also a turning point, a ceremony to show the world you love each other. A way to make it more official. I want to marry a man I love to say I want to spend my life with him.
For me it doesn't have to be just one person, that's a monogamous thing, and I'm not monogamous. For me a marriage has a significance of commitment and investment, and you're saying you're here for the long run.
I don't think marriage is necessary, but I don't see it as meaningless either.
I want to have a ceremony for partners other than my legal husband. They'd be my husbands too, as far as I'm concerned, and I'm really not too worried about the fact that they wouldn't be equal before the law, since the law isn't really what matters.
Hope that helps you understand my position here.