Bingo.
What follows is going to be provocative, and probably not completely correct, but...
One unintended result of this explosion has been the devaluing the meaning of a baccalaureate degree in some ways.
The hard truth is that IQ is distributed normally. That means that about 2/3 of the population has an IQ within one standard deviation of the mean IQ. "Back in the day," when 20% of high school graduates went on to college, that meant that college graduates with bachelor's degrees tended to be smarter than average. By and large, that's not true any more.
Now, "smarter" does not necessarily mean "a better employee" or "more successful." There are other factors at play here (can you say "work ethic," or "motivation," or "discipline," etc.?). But in 1975, if an entry-level kid had a BA or a BS, you pretty much knew that there had been an intellectual "weeding out," and that kid wasn't a blockhead. Now... not so much, frankly. BA or BS now really often means "mediocre." It has to, if most of the people earning that degree are of middling intelligence.
So... it's not at all clear, any more, that obtaining a BS in, say, management, or a BA in psychology (feel free to substitute any number of other majors here!) adds enough value to justify the cost - especially if the cost involves a large amount of debt, at interest rates driven by financial institutions' need for profits.
A technical degree (engineering, computer science (programming), etc.) may still make economic sense, since there still appears to be substantial thinning going on in those majors at many institutions (e.g., kids without the aptitudes change into other majors) - but typically, kids in those majors no longer have the opportunity (or inclination?) to use electives to build a broader foundation - which limits their subsequent ability to move effectively out of the purely technical career (engineer, programmer, etc.) into technical management or policy-making (corporate or public).
"Back in the day," even a BA in English Literature meant something. It meant the candidate had survived the basic weeding out process, had learned to compete in that 20% environment, had probably learned to think. Those graduates might not find careers in English Literature, but they had generally acquired reasoning, organizational and disciplinary skills that rendered them useful in responsible white-collar careers.
Now? The typical graduate (not all, but the average one) has a middling IQ, and has done enough - often, just enough - to graduate from an environment populated by their peers - other middling students doing just about the have to, to graduate. There's not a lot of weeding out going on any more. So you get liberal arts graduates who are not only functionally innumerate, many of them cannot write - not well enough to craft a serious business case or policy document.
And the thing is, a lot of these kids will wind up in careers where they don't really need strong math or communications skills (since they don't have those skills, they'll wind up in careers that don't require them, one way or another). They won't be highly lucrative careers, and if the kids are burdened with large student debts, they'll be handicapped for decades. These are kids who went to college "because it was the thing to do," not because they were really interested in careers that require the skills that bachelor's degree holders once could be pretty much assumed to have.
Yeah... and there always were. It's just that, in 1970, those "very few" college students (the "serious" ones) made up a significantly larger share of the university population - and that changed the competitive environment for all the students of that time.
