Are children really 'inferior goods'?

The article - Are children really 'inferior goods'?  published by THE WEEK, on July 5, 2011, states opinions weather children are important or not for a couple/ family. In perspective of an economist, he mentioned that as people make more money they neglect having more children; conversely to normal goods that are needed more and more as people get rich. This idea is also advocated by Catherine Rampell, who feels that if kids were advantageous, rich families would want to have more. She sustains her opinion by comparing people with high annual income, who need less than 3 children to those with average or low income who say that want at least 3 or more kids. Another opinion by Karl Smith see the inferiority of kids in different angle. He pointed out that people are replacing children when they are getting richer because their time become scarce and the amount of work also increase. This have an direct implication on their businesses and education, once they have to stop and devote more time to the children. The final remark by Sierra Black, states that the issue of kid's inferiority should not be seen isolatedly with mere economical analysis. There are more other factors that are taken in account whether or not to have large family. 

First of all, I am wondering why the author and other economists are comparing human beings with acquired properties. In my opinion this is unfair comparison, yet a kid/person does not have a price, ethically cannot be sold or bought, although the trends in nowadays indicate that some people can sell or buy a person. I think we are becoming more altruists insofar as we put the wealth above everything. For me it makes more sense if a rich person has someone to share with his/her wealth. And generally these people are family members.

Another reason to not compare kids with simple goods is the emotional side that people should have. Money doesn't do everything we need, mainly when we are becoming older. We need companionship. I believe that if we compare older people living in retired centers with those who live in the family houses with son/daughter, grandson/granddaughter are more likely to have great satiation with life. That means increasing the size of family member, the chances of having more companionship is high. 

However, I agree with Sierra Black, when she says that other factors are considered to have big family size than just economical argument. It is not fair to have many children without giving them adequate conditions to grow well and also is unfair to neglect having children because of lack of time or people devote too much time working. We need to balance and I think there is enough time for everyone to do everything, just a good plan we can accomplish our personal needs and moral obligations. Otherwise the human species will become extinct.