Everyone should do what is right for them and their family, but should have the sensitivity to realise that what is right for them isn't necessarily the way forward for someone else, and to make crappy judgements about others (and this applies to SAHM, WOHM, bf/ff, etc.) just looks like defensiveness and jealousy.
I am a SAHM at the moment. When my youngest is at secondary school, I will try to find something to fit in with those hours, but I will still be at home for my dc when they come home, so they know I'm there for them, and yes, this decision comes from the fact that my parents (not just my mum - I have two parents afterall) both worked long unsociable hours, so until I was 9, we had nannies to do everything, and after that age pretty much fended for ourselves.
I was bullied at school and couldn't talk to my parents about it because they just weren't there, and when they were, they wanted down time from working long hours, the last thing they wanted was to hear the mundane details of my shitty day, week, term or year at school.
I want to be different for my dc, and part of this is being at home for them - don't get me wrong, I'm not a slave to them, I have my own life, but how I feel about my childhood has made me make the choices I am making now.
My dc will probably all resent me and decide to work full time, but such is life. Most people get to a certain age and question their parents choices, it's only natural, as you compare them with the choices you make for yourself.
I don't think I'm any less a role model for my dc by being at home for them. Dh works full time, we have found the balance that suits us, and hopefully together we are doing the best for our children and our lives.