This is such an emotive topic, but I really feel that there is no 'one size fits all' approach.
Everyone has to do what works for them as an individual, and as a family, be that being a SAHM, working full time, private, state, whatever. There is no 'right' answer, and no 'perfect' solution. Every family has its cracks and problems. Every family is different. For some, being at home with your kids full time is not an option, financially or sanity wise. For some, leaving your kids every day would be too much to bear, and no career would justify it to you.
I have been a SAHM for almost 5 years, but am returning to studying next year, followed by full time work after a year, (although I will be fortunate enough to have the school holidays at home...). I am SO looking forward to it. I cannot wait to get back into working, and I absolutely love the job, so it is a good thing for our family. But I would never judge someone who chose to be a SAHM indefinitely, or one who works 8am-7pm 5 days a week.
I also think it is a sad state of affairs when a SAHM is not considered a good role model. Of course we want our girls (and boys) to grow up to be motivated, eager to learn and do as well as they possibly can, in whatever they choose to do. Of course I would love it if my daughter followed a career in medicine, or law, or whatever. But the constant pressure to 'have it all' is so sad, and to me, staying at home with your children is certainly not a waste of a good education, and I absolutely believe those of you (including me, for now) who are SAHMs are good role models. Being a working mum does not make you a better mum. Being a SAHM does not make you a better mum. We are ALL good mums. Our children are all loved and nurtured. Really, isn't that all that matters?