My mom and both of my grandmothers lived in a world where the dual income household is the norm, and has been the norm since the 50's, but since the 80's and 90's, there has been a retrograde shift because for a while, being a stay-at-home-mom became a status symbol. However, all of my cousins, male or female, are part of dual-income households. (They all live in Shanghai.) But that's a much longer rant and off-topic to the current discussion.
But +1 to your initial point, re: effect of dual income households on the economy.