I sort-of agree, in general - if I'm honest with myself, I think it would be optimal to be with your young children, and that mothers are the first attachment figure so it makes sense for it to be a mother.
However, life is not optimal, not 'best'... and I went back to work after a year with each of my children - mostly for my own sanity, rather than any need for money (in fact with my second, childcare was more than I earned, but I viewed it as an investment).
I am more than happy to be a less-than-optimal mother. I do my best and it will have to be good enough. I also occasionally feed my children junk food and they watch far too much TV. But they are loved, and happy, so...
There is way too much pressure nowadays to be a totally perfect parent, especially mother, in my opinion. Articles like this one fan the flames.