Traditional gender stereotypes aside, I can see why having one partner concentrating on earning money and the other concentrating on children and home stuff could have advantages. The first can be more focused, freer to take whatever job opportunities come up etc, and potentially earn more for the whole family's benefit. And the second can be more focused on the kids, properly there for all their needs both practical and emotional, and so on.
DW and I probably have the most equal and gender-neutral marriage it's possible to have. We both work freelance at almost-full-time hours, and arrange our contracts and business to share being here in the mornings to get the kids to school, and in the afternoons to be here with them, take them to clubs etc. At the moment she probably works slightly longer hours and I do slightly more with the kids, but that varies over time with changing work situations and needs.
But TBH, there are times when I think I'd be happier for her to go properly full time and me to be a SAHD. It's hard to make the most of employment and earn proper money when you've got to be home by 3.00 rather than 6 or 7, and I find myself less effective and involved with the kids when I've just done a hard day's work. There's a lot to be said for choosing one and doing it properly.
I suppose the flipside of that is that traditional family structures can lead to marriage partners not understanding each others' lives and feeling anything in common with each other apart from the kids. So it's horses for courses I suppose. Whatever works for you.