Many professors will cite "neoliberalism," because neoliberalism is by definition the boogeyman that ruins everything. But they don't usually offer anything like a falsifiable or verifiable theory of how neoliberalism did so.
My alternative take: The push to make college more universal combined with increasing costs killed college. Here's why: For various reasons (Baumol's cost disease + administrative bloat caused by a principal-agent problem + additional expenses incurred by increased regulation), colleges have become ever more expensive. As they become more expensive, the need to get a positive ROI increases for students. Further, as we pushed more and more students to attend college, and in the past few decades flooded colleges with ever more marginal students, the signaling value of the degree in the market place goes down.
In 1960, when hardly anyone went to college, graduating with an English degree from a non-flagship state school was an impressive signal that could get you a good job. By 2020, when most high school students go to college, and when many colleges have dumbed-down their classes to accommodate marginal students, graduating with an English degree is not so impressive to the outside world. So now many students at non-elite schools have to major in "practical" fields to signal their quality to employers.
Note: I'm not saying colleges are or should be job training programs. I'm just describing how the incentives work out for students. In 1960, you could afford to study literature at some SUNY directional school and it would work out for you.
Nowadays, you can't.
So, oddly, one way to make the liberal arts more attractive would be to reduce the total number of students.