I know, but I think the story is misunderstood in the first place. I think that he was just trying to show them that it’s inappropriate to go to a Gadol Hador to help you with your homework.
Alternatively, he realized they were too into their schoolwork, and he wanted to make sure they realized that there are other important things.
Either way, I don’t think the point was that they necessarily had to know how to make a potato kugel. I’m sure there have been plenty of tzadeikesis who had wonderful marriages and were wonderful wives and mothers even though they knew more about Ramban than about potato kugels.
In some homes, the husband does the cooking and there is nothing wrong with that if both the husband and wife are happy with it.
Of course, when someone is married, their most important job is being a good wife and mother, but there is room for individuality, and it sounds funny when you phrase it the way you did. Also, before marriage, there is certainly no reason why a girl can’t spend more time learning Rambans than making potato kugels!