As regards Will's statement "The collapse has coincided with a retreat from marriage ("the proportion of never-married men was over three times higher in 2015 than 1965"), which suggests a broader infantilization.": This is no doubt partially true, but it's also the case that people never meet the right person. They're not interested in what they can get and they can't get what they want thus no marriage. If they're is a solution to that I'm not aware of it.
The key issue is the economic concept of marginal utility.
While not everyone will act strictly in their economic self-interest a large number will be heavily influenced by it.
Kids more expensive than not having kids?
Marriage more expensive than not being married?
Differences between handouts and wages smaller and smaller?
All of these affect behavior at the margin.
If you think of economic behavior as a Monte Carlo simulation and create policies that have these affects then millions and millions of people will be shown to have changed their behavior.
We are suffering the consequences of eighty years of government incentives not to work, not to marry, and not to have kids.
It is just that simple—and just as easy to reverse.
Bottom line: Trump 2016!