From a practical point of view, I think it makes sense to be married For the legal protections, especially If you have kids.
Saying that, if we ever divorced or DH passed away, I would not marry again. I would possibly have future relationships, but not marry, as I want to protect my sons inheritance.
I knew that I wanted marriage, and told DH this early on. He thought it was just a bit of paper, but, as it was so important to me, he asked me to marry him.
I see so many women have children with men who dangle marriage like a carrot, and honestly, I find it really sickening