The white middle class family in America has grown ever more paranoid over the course of my lifetime. Children once roamed free after school, but now it’s virtually a crime to leave a child unattended in public. It’s not clear to me that there has been an epidemic of child abduction or molestation by strangers. In reality, the person most likely to molest a child is that child’s own father, followed by trusted adults such as uncles or priests. The people most likely to abduct a child are their own mother and father, in the midst of a contentious divorce.
Perhaps not unrelatedly, leaving children any unstructured free time is a sure way to thwart their chances of moving up the meritocratic ladder and build a life for themselves. Strangely, though, the meritocratic lifestyle seems to be a perfect way to keep the child from growing up at all, thwarting their life chances in an entirely different way.
In both cases, an outside threat is hallucinated in order to cover up the fact that, in the precise area where the nuclear family is supposed to be protecting the children, the nuclear family itself is the true danger. How can we account for this strange phenomenon?
By the late 1960s, it was already clear to many observers that the nuclear family thing wasn’t working. Feminism was producing major changes in its practical economic structure, young people were making different demands on potential partners, and queer communities were beginning to resist their marginalization. In response to these attacks on the nuclear family, we suddenly learned that the outside world was an incomprehensibly scary place, full of men in vans and transition lenses and competitors with much better college applications, and many came to view the nuclear family as a kind of nuclear bunker. In reality, though, it remains what the Baby Boomers, for all their many faults and failings, initially perceived it to be: a prison.
An und für sich 
Wouldn’t the conclusion of your argument be to abolish parenting itself and not the nuclear family? Isn’t the most intense and bizarre helicopter parenting associated with upper middle class “families” that frequently have “non-traditional” structures, such as two working parents, mom and dad have different last names, two dads, two moms, a dad who is merely a donor of genetic material, etc.? Most of the actual nuclear family fundamentalists I know want their kids running around in the woods alone starting from the age 3 learning survival skills, and all of them are crack-shots with a rifle by the age of 5.
In fact it seems to me most helicopter parenting emerges from anxiety about no longer having an “authentic” nuclear family structure.
The growing precarity of middle class families must have something to do with it. The risk of injury or some kind of accident that would lead to medical bills or make a parent miss work are likely as important, if not more important, than paranoia about child abduction
I think there are some amazing observations here even if the last paragraph feels a bit forced to me. Innovations like attachment parenting and conflict resolution strategies have made nuclear families far more nurturing for many people. The comment about financial stress is also an excellent point.