On the other hand, I don't think you can ignore the financials. It's not about "useful vs useless." All courses of study are useful. People are getting saddled with piles of debt that they can't manage, though, and US law doesn't allow you to declare bankruptcy from your student loans, so people can potentially end up screwed for life. Against that kind of a backdrop, to blithely charge students whatever tuition they're willing to pay, regardless of whether or not they can expect to be able to pay it, is heartless.
So then the question arises, how do you increase the chances that nobody gets shackled with unmanageable debt for life? Changing the earning power conferred by different majors is a possibility. But, capitalism being what it is, that's going to require either changing the demand for those skills, or changing the supply of people who have those skills. It's hard to imagine how the former can be managed without some sort of government subsidy.
There are myriad ways you could affect the supply side, though. Doing something to put universities on the hook for how much their students earn, such as having students pay a % of their income to their alma mater for a decade or two in lieu of all or part of their tuition, would certainly do it. Universities would hopefully respond by starting to limit the number of seats available in departments that feed into less lucrative career paths right quick, in order to make sure that every department is financially sustainable. That would, in turn, reduce the supply of people with those skills, which would translate into an upward trajectory in how much it costs to hire someone with those skills.
But what is that kind of approach, if not a distinctly capitalist riff on the idea of "delineating useful vs. useless degrees"?
I keep wanting to reply to your comment because it's a good one that seems like it deserves more than just an upvote. But I also don't want to take the time to write the kind of response you deserve. So I'm leaving this meta comment just to let you know you weren't shouting at the wind and to thank you for your thoughts, which I found very interesting.