Side note: If college education was "free," it might encourage faster re-skilling and more "profitable" to society.
A large part of the problem is that, in a glut of labor, employers use degrees as litmus tests of commitment rather than ability. If you can just ignore anyone who doesn't have a bachelors, you will, because why not? But that doesn't mean the bachelors is, at the macroeconomic level, worth it to society to push everyone to get.