I am a SAHM and proud to be one. For the record, I have a PhD in a really high-falutin', poncey subject from Oxford and am/was an 'intellectual' (without wanting to out myself). I put no less effort, passion, research, slog, dedication and heart and soul into being a full-time mother than I did my academic work - much more so, in fact, as giving my child all the best of myself is far, far more important and rewarding and a testament to my prowess, worth and status as a human being than any of the smartarse stuff I did before. My brain hasn't gone to mush because I am intelligent and find ways to stimulate myself. Working for pay has nothing to do with staving off intellectual atrophy.
As a feminist, I find the attitudes towards SAHMs incredibly insulting and ignorant. We cannot say that Feminism has benefitted any part of society if we do not and cannot view stereotypically and traditionally female rôles, behaviour and activities, etc., positively and with equal worth to anything deemed worthy by patriarchal thinking. Put simply, seeing being a SAHM as somehow inferior, demeaning, ruinous for the intellect and ego, etc., etc., is incredibly misogynist and it's saddening and maddening to see women falling for all that crap and not just feeling that way about other women but even about themselves. I find the placing of importance on status, job and wealth incredibly immature, boring, pathetic and a sign that a person feels deeply inadequate within themselves.
Also, please let's be clear that being a SAHM does not automatically mean you are a domestic skivvy. The only housework I do more now than I used to, is more cooking and washing up in the day in order to feed me and my DS.
If someone feels demeaned and inadequate by being a SAHM, then that is all about that person's own self-worth and personal issues. They need to get help for their own personal problems, not impose them as the supposed truth for everyone else on the same position as them.