I see why you are perplexed - I would be too. Especially if a family has children, I think it is best for the wife to be home. If a family just cannot make it, then I think it's OK for a wife to work - or when the children are bigger but I still think a woman's primary responsibility is to her homestead. I work because we just do not make enough to live on just my husband's salary but I work for the church - and I do things that are important AND I mostly make my own hours and keep my kids with me. I'm able to either work from home (website stuff) or in the sanctuary during the week (computer stuff) and bring the kids.
But to encourage two incomes when it's not "necessary" is not all that Biblical, IMO. We should be encouraging our families to get out of debt, understand what is "necessary" and what is "wishes and wants" and just how to deal with the two. Unfortunately where we live, many families have both spouses working out of necessity due to high cost of living here. Just our property taxes alone are $14,000 without our clergy exemption - and the exemption only brings that down to $11,000 a year. But being creative, it's possible to decrease the expenses - but we must be willing to do that. We've been ready to sell our house at any time if needed (although it's fully paid off so that's a blessing) to downscale and we'd go to two older cars if we had to (although they're getting there anyway as they're 1999 and 2002).
I guess it's priorities for each family, you know? I have a friend who complains about living in her parent's basement - but they have the best of every electronic you can think of. Their 17 year old has gone through atleast 2 cell phones a year and is now at a Blackberry, they bought her a thousand dollar camera for Christmas and so on. Yeah, we have a house and my kids have a point and shoot and a prepaid cell phone (that they pay for on their own). That's their priority to be all up to date and it's our priority to have our own home and be out of debt. *shrug shoulders*