Even if a man is planning on having children there are few reasons to get married (the downside risks outweigh the possibility of benefit). Name a benefit a man receives that he doesn't already have by virtue of the standing relationship. Perhaps among them would be:
-1- the ability for a wife to visit you on your deathbed when you're unconscious
-2- the ability to pass government-sponsored survivor benefits to your wife
... I can't think of many more, but would like to hear them.
For a man the only way to make a custody situation worse is to throw a marriage dissolution on top of it. Without marriage he at least retains the equity he has built up. Granted, if the wife outearns the man then the pendulum would swing in the other direction.
If you want children then draw up a private contract between the mother and the father rather than deal with the blanket contract that the state offers (the clauses of the state contract are never clearly stated - family court decides for you upon dissolution of the marriage; so you won't know until then).
In your own child-rearing contract clearly state what is required of each parent. Also state what conditions and responsibilities will prevail if the two parents decide to abrogate their initial contract (a 50/50 split of time would seem to be most equitable but if the parents dicide differently then write it up and commit in writing to it).
You do raise a valid question: "What really is the purpose of being married?"
And "everyone should at least try it 2 times" would be humorous if it weren't so succinctly, though sadly, to the point. There are some to whom it means so much that they never do it; and others to whom it means so little that they do it with as many spouses as possible.
My opinion a MAN truly needs to be married more than a woman especially if a man has been married to a woman who he feels very sexually attracted to, someone who does his laundry cooks his meals, handles the mundane household tasks and hangs out with him like a "Bud" when that woman is gone those men are usually devastated in a pretty bad way.
Would it be possible, in lieu of a prenup which may do little to the settlement, to sign a contract that says a majority of the guest list of the wedding must agree to any divorce settlement?