To be brutally frank, middle class can no longer afford a stay at home wife.
That is basically an upper class thing. The price of everything went up over the decades, especially housing, and there are way more bills to pay than there were 50 years ago while wages have been slashed in half by women workforce, than slashed down again by infinityjeet imports.
So it is not really a preference thing, more of a thing that 95% of men just sadly can not afford. Or if they can, it would be a situation where the woman would be unlikely to like all the privations such a lifestyle would put on the family, basically pushing them into the lowest class of poor.
I had seen a single income middle class family in school, all their kids wore the same set of clothes handed down from the older kid. Say goodbye to vacations, new clothes, brand shoes, get used to public transport, etc etc.