Shibuya Me, (and even GomiGirl), I think your opinions are good ones but I think they will change if you ever get married and have kids. You won't care so much that your wife or yourself are contributing to the world and helping people. You will realize that your first job, the one that is most important to you and to the world, is that you properly raise and educate your children.
You won't view a stay-at-home wife as someone who picks up after her husband. Most married couples have children: You'll view a stay-at-home wife as someone who loves her kids too much to allow them to be raised by strangers at the day care center or hoikuen or yochien or whatever. I am self-employed and am at home most of the time as well. Trust me, it makes a huge difference in the kids' lives (and the parents lives).
As the kids get older and spend more time in school and are more independent, then parent should feel free to get back to their own lives. But until then, the best thing they can do for their kids, themselves, and society, is to spend as much time possible with their kids.
-Slim