This is strengthened by culture: look how the marriage is presented in the movies, for example. The woman is anxious if he's going to propose, then he has to buy a very expensive ring just to propose, then she is extremely happy as if she won a lottery (not because he loves her, but because he decided to marry).
https://www.nytimes.com/interactive/2015/04/16/upshot/marria...
High income couples are actually penalized, and even worse off once they have a child!
You all make it sound as if stay at home women was the norm, but it is not the case.
Looking at my friends there's a pattern, a man who loses his job long term becomes divorced quite quickly. So there's no added safety for the man and no economic incentive (or even a disincentive, not sure how bad it really looks for men losing everything in court).
It's slightly easier to get a large loan or mortgage as a married couple, but it's not exactly impossible if you just live together as partners.
The way I see it, it's an absolutely enormous expense with almost zero financial/economical benefit for us. I love my partner and want to get married because I think that's the right thing to do, but if I looked at it outside of the "romantic/traditional" angle, there is absolutely no reason to get married.
You also benefit from spousal privilege, meaning you can't be compelled to testify against the other. Although, depending on your criminal inclinations, that may not be a strong reason to get married!
Now, you could argue that I could have gotten the same deal without marriage, just living with her for. But first, I could not have gotten that deal - not with her. It was marriage or nothing. And second, I didn't want just living together either. I wanted the real thing, with the commitment. I wanted to commit to her, not just to an institution or a tradition.