Xenia, you are 'Susan from London', right?
I agree with the article and with Xenia's posts. Even in the most stable and loving marriages things happen which can completely throw the family finances. It's common sense to nurture your earning capability, even if it means reducing it somewhat in the main childcaring years.
The fact is, it's only in the past 100 years or so that women haven't worked once they had children, except in the upper classes, where the men didn't work much, either. Women just strapped their babies to their backs and went back out into the fields.
However believing that the article is true doesn't mean that it's right to just accept that this is the way life is. I am lucky in that both myself and my husband work part time to support our family, and enjoy both fulfilling careers and time with our children. We earns the same as we would if he was slogging his guts out full time plus, and I was twiddling my thumbs getting bored at home. Not everyone works in industries which would support flexible working like this for women and men. They usually could support it, but don't, because the men and women don't push for it.
I read an article at the weekend about schools offering extended hours care for children and one commentator said something along the lines of "instead of/as well as developing work-friendly schools, shouldn't we be concentrating on school-friendly work?" I couldn't agree more.