Let's accept your assumption that colleges teach things that are of value in some non-financial sense. Colleges make society better or make people happier. Then we should expect to see an improvement in a King of Bhutan-style Gross National Happiness rather than a reduction of inequality or an increase in GDP.
If Americans aren't, on average, happier than they used to be (adjusted for income), then the conclusion should be "there was no return on the investment in broadening the number of people attending college"
"Unemployment rate for Physics PhDs is just under 10%" -- that sounds pretty bad if you assume that someone with a physics PhD is smarter than average and has more years of education than average.
That the average person who pursues a job is not very successful economically does not mean that the job is not worth pursuing for someone who is thoughtful and talented. As noted above, if the median child support is only $6000 tax-free dollars per year that suggests that high-income potential fathers are an underutilized resource.
http://www.bls.gov/ooh/computer-and-information-technology/c... shows that the median computer programmer gets paid $75,000 per year. That doesn't stop thoughtful and talented programmers from earning a lot more (though collusion by employers, e.g., Apple, has interfered with what would have been a market).
http://datacenter.kidscount.org/data/tables/106-children-in-... says that about 35 percent of U.S. children live in single-parent families or 25 million children total. In any case, the fewer the number of women competing to collect child support from high-income men the higher will be the returns to that strategy and the more attractive it will be compared to working for wages.
That section of the article is not about "alimony" (may require years of marriage to obtain) but about "child support" (requires one night of work to obtain).
If Americans aren't, on average, happier than they used to be (adjusted for income), then the conclusion should be "there was no return on the investment in broadening the number of people attending college"