What's so special about the family ?

I recently talked to a lady who held that practically everything that I listed in my (random) 10 reasons for polygyny could very well be done in a monogamous marriage or even without being married since some social group or another was just as good in taking care of the elderly, supporting you in your home schooling efforts, etc., as long as people chose to treat each other with love and respect. I disagree. Here is what I think is so special about the family:

Our approach to the family is purely biblical. The vision of the family that we have is multi-generational, and that does not only mean that many generations live under one roof, but that the vision is meant to sustain the family for hundreds of years, a vision for our children's children's children, and their great grand-children, too. Think of the promise given to Abraham, and whom it concerned.

The family is the place where all social responsibility used to be placed - care for the young as well as the old, education, work, etc. etc. etc.. This is an ideal we are restoring: We are building a
household. No other group of people, whether they are bound together by ideology, common interests, creed, race, vicinity (like a neighborhood), common fate, employment, etc. has ever been or will ever be able to substitute the family adequately. Groups like this as well as the state institutions that have taken over the responsibilities of the family (like schools, nursing homes, etc.) are weak, inadequate, mediocre, and short lived.

The family is more than just a group of individuals that happens to live under one roof for a time.