Each family makes the best choices for their own family and own situation. Certainly, some are more 'forced' than others, due to financial needs, but that does not make the stay-at-home mom's work any less valuable.
http://www.washingtonpost.com/blogs/election-2012/post/ann-romney-responds-to-democratic-pundit-saying-she-never-worked-a-day-in-her-life/2012/04/12/gIQApstpBT_blog.html?hpid=z2