I think it is economic and educational and the norms shifting. Their circumstances are increasingly implausible and things are pretty decomputerized. They have accidentally become a period piece as time passes them by.
While the house quality varies according to gag it is a large and well appointed house with one income from someone without a college degree from working at the plant in a physically undemanding is if not anchronistic increasingly less and less everyman representative. Even married people who are well off tend towards dual income households these days for one. The economy is far more service than industrial and the industrial has largely skilled up and automated. And that goes without discrediting of so many past tropes by time. Well meaning wholesome dolt manages to fail to fit the milieu in many ways and has been considered still overused decades ago even with their disapperance.
While the house quality varies according to gag it is a large and well appointed house with one income from someone without a college degree from working at the plant in a physically undemanding is if not anchronistic increasingly less and less everyman representative. Even married people who are well off tend towards dual income households these days for one. The economy is far more service than industrial and the industrial has largely skilled up and automated. And that goes without discrediting of so many past tropes by time. Well meaning wholesome dolt manages to fail to fit the milieu in many ways and has been considered still overused decades ago even with their disapperance.