In a traditional sense, marriage provides stability and permanence. Having a large gathering in front of many people, then putting it into law or religion provides that layer of permanence. That is the goal anyway...
The civil rights movement and welfare state basically ****-canned that whole idea and now marriage is no different than getting a new car. I get why people do it, but I can't say that I would do it again or recommend it to anyone I know. I always fear the complacency that could potentially manifest as a result of that comfortable permanence.
Marriage is important when one thinks abt one's future offspring.
If you got a daughter, she will need her mother to learn her manipulation skills and a father to lay down the law.
If you got a son, he will need his mother's overprotective shield when he's a toddler, understand the meaning of love through her and from his father the ways of men.
It's always incumbent upon a man to lead his family AND IT STARTS from choosing the right kind of women to start a family THAT wants to be led by him.
The problem that I see, for most part, is that many men are not up to that task.
Maybe because of that, many policies by the state was created to circumvent the generally poor leadership of men.