Marriage, the legal contract... because in america there are few communities who actually enforce monogamy and keep the couple on the straight and narrow. So, the legal contract, between the married couple and the state, has no benefit for the man. (unless he is literally being mr. mom, where she makes all the money)

The legal agreement gives the women all kinds of rights and privileges and most of these are taken from the man.
It gives nothing to the man.

Further, the marriage contract is updated periodically, with the man having no say, making it worse and worse for the man.

And the biggest thing people say is that without being married, they aren't your children. Well, actually, if you are not married you have more rights to see your children, and a court that isn't completely against you seeing your children.

So, who, in their right minds, would enter into a contract where everything he gives is set into law, and everything she gives is by her free will, and if you bother her too much (or even at all) about it, that is considered abuse?

There is nothing, legally speaking, that a man gets in a marriage.
Except the ability to go to prison without a trial.