The Institute Of Marriage: Is It Obsolete?

This being the 21st Century, is the institute of Marriage obsolete?  I know that back in the Middle Ages, when the Church ruled the land and made the laws,  it seemed to be a good idea for people to have a relationship solemnized by said Church.  But with more unmarried couple living together these days, both straight and gay, Maybe we should rethink our ideas of what relationships should be, and if Marriage is needed any more.  I see no problem if a couple wants to have their relationship blessed by a
church, but if I was in love with someone that I wanted to spend the rest of my life with and have kids with, why should I need a piece of paper to legitimize my relationship? And if and my significant other wanted to go that route, we should have the right to do so without critcism.