Every family is different. How I was raised was different than how I raised my children. But what worked in my house might not work in others. But it worked for us.
I stayed home, and I worked. My husband always supported me in either endeavour. We didn't have anyone to watch our children before kindergarten so I got to stay home. We could have done day care but the rates at the time for infant and toddler care would have eaten the second pay check. When the youngest turned 4 I got the itch to work. I just wanted a life outside of the home. My husband supported my choice and helped around the home and with the children. I worked part time. I eventually worked at their school so I had holidays and summers off with the children. For me I had to do both. I got to be a mom for my children and got a career. I personally found having both as the most fulfilling choice for me. I believe I was and am a better mother because I had another vocation. Working made me really happy. Having extra money made life a lot easier. Having a husband who was willing to help made a big difference in my choice to work. He would make dinner and change diapers. Very supportive. Even when I wasn't working he helped. Having a career gave me a sense of accomplishment that made me so happy and centered that I brought that to mothering.
So I think that for some family units, yes it's great if a parent can stay home (plenty of daddies are staying home too). But sometimes it's okay if both are working too.