Strongly disagree on "do not want children there is no point in getting married."
There's an emotional reason to get married, formalizing a life long commitment. That's a big one for a lot of folks (citation: my marriage).
But lets say you're not a feelings type of person, and those arguments fall on deaf ears. If you live in a community property state marriage makes inheriting assets ridiculously easy and avoids all sorts of taxes. (otherwise you're down the road of setting up trusts which will incur lawyer and trust management fees).
Taxes are another one - if there's an income disparity. Filing jointly with a single income does wonders for what you don't have to pay.
Your spouse can also not be compelled to testify against you, which depending on how paranoid you want to be might make you sleep better at night.
To say there's no point is missing the point though - as much as marriage is enshrined in legal rights which are unavailable to those who do not marry, the institution of marriage is centuries old and exists in many religions. There's an emotional reason to do so, and that's point enough.