I blame dishwashers.
No, really. They (along with refrigeration, gas stoves, clothes washers and dryers, vacuum cleaners and mega-grocery stores serving prepared food) created too much efficiency in the home, thereby reducing the economic value of traditional housewife labor. This should not be a shock. GM replaces workers with machines all the time because it is more economically efficient. Indeed, doing things the old way generally is less efficient, and markets abhor inefficiency.
Decades ago, husbands could support a traditional household because the labor supply required adequate compensation to cover the expense of the work performed at home. As that home-labor cost (in woman-hours!) decreased, the male laborer's wage no longer had to cover the expense. As a result, males became able to work for less so the supply of less costly male labor increases in the market. At the same time, the under-used female labor supply entered the market, further increasing the supply of labor outside the home. The result is lower wages.
Now I certainly recognize that stay-at-home moms do a lot of work. But ... at the same time, to achieve relatively the same standard of living between 2000 and 1900, the amount of household work has decreased markedly. Has anybody seen the PBS show 1900's House? Hours of handwashing clothes, hand wringing, line drying, and hot iron pressing is now handled with a 15 minute permapress cycle, plus 65 minutes in the dryer. Daily trips to the green grocer, the butcher and the baker are now done in two hours per week at the supermarket.
So I blame dishwashers. Dishwashers replaced women, so women could replace men. Equal pay laws or female access to higher education are not to blame. Rather, blame good ol' American capitalism's market efficiency.
JADVirginia