See in regards what you have built up PRIOR to a marriage, I agree with you to a certain extent. Ideally you would both be bringing a certain amount of security and assets to the table.
Many women are performing really well compared to men in their careers before children - its having children where it falls off a cliff and creates the sex wage gap.
(Ive seen too many videos of alpha dudes going on about women earning more, and no such gap - but they do tend to only look at the pre-children women)
Its AFTER children that the problems come - as in OPs case here. And a consideration as to whether a woman's value in regards bringing up a family that they both wanted has value that is beyond bringing in a salary.
Maternity leave often sets a pattern that seems very difficult to get out of - woman at home with the baby starts picking up more and more of the traditional role. Man gets into the habit of doing less and less, because 'logically' she is at home all day so she SHOULD be doing it (Ive heard this argument, and its hard to argue against.
Woman needs to go back to work. Typically there seems to be a lack of discussion with man about who will do pick ups/drop offs and so so many times men 'Just Cant' because their important job doesnt allow flexibility (or he hasnt asked, but thats a good excuse) so this causes a big imbalance work wise, or a mum run ragged.
For the man it seemed better for her to stay home, or just work part time, especially if there are more children, because then he doesnt have to pick up the slack at home/have demands about childcare, and the wages of these reduced hours or work thats flexible around children doesnt go far when balanced with nursery fees. And its not really until secondary school that supervised childcare ceases to be as important (well Id argue not but.....)
This leaves a position where a man can progress in his career unhindered, knowing all is being handled by someone else at home. Meanwhile she may have taken potentially 10+ years off the career ladder and will never be able to get back to a level she may have been at previously, never mind going further. Mothers are seen as a problem in many workplaces - potentially taking time off, needing flexibility, whereas ironically men with children are seen as more responsible, and often it does their careers good.
Now if you are married, these choices and decisions mean that the unpaid labour that women are doing - physically having the children, taking time out, taking the financial hit to their careers and carrying most of the emotional burden of running a household whilst supporting her partner to succeed - these are balanced by the financial security that they are building something together - that her contribution is recognised as being as significant to the family whole as the man's higher wages.
If you are not, you are taking a mighty leap of faith, surrendering all that free labour and future career on the hope that he wont bugger off and change his mind, and you will literally be left holding the baby with 100% responsibility. Or even worse, bugger off as the last one leaves home for Uni, and your 'useful free labour' is finished and you have spent years being an unpaid housekeeper/nanny/etc and now find yourself homeless and with no career whatsoever, or chance of building a pension.
Im not hearts and roses about marriage for its own self. But if you are planning a family, I think its the decent thing to do. Its a big ask for a woman. Its a commitment to be a team to build it. Her role is not insignificant.