I see nothing at all wrong with it. In today's society, couples have to really pitch in and do whatever it takes to make it. If the Mom is the one who can earn the better living, and they are comfortable with just her income, I see nothing at all wrong with it. If the children are young and not in school, think about the daycare expense that is saved.
Mums and dads who can organise to stay at home (cottage lifestyle) or work at home are doing everyone a favor. Working on a vegie garden, home schooling, DIY projects, low driving kms, are all other ways of life better than the rat race.
My husband has been a stay at home dad for the last eighteen years. you just need to set rules as to who does what and stick to them. If he is to do the cooking, shopping, washing or whatever, don't start doing them when he doesn't do them exactly the way you would have done. you both loose out that way. realize that everything won't be done "your" way and live with it. otherwise you will end up taking over his jobs, and you will resent it. And he will let you do more and more of what is supposed to be "his" job. Then he will feel guilty. it's a loose/loose situation. Decide who does what and leave it that way. and NEVER make him feel he isn't contributing just because his "job" doesn't pay any money. His contribution is in helping you to go work for pay and lift some of the "homework" off you.