We could produce 20 million PhD's in art history per year and it wouldn't create a single job in art history that would pay the cost of getting the degree.

You are right.

Don't get me wrong, no education, spending time at an endeavor that you aspire to is wasted. It's just that some talents are more in demand than others, and will therefore, pay more.

I remember sitting at my son's graduation at UNC-Chapel Hill, back in May,2005. There were more students graduating from the School of Journalism than all other schools combined. My son graduated with a degree in Information Technology.
The thought crossed my mind, if this is typical in higher education, I could spend sixteen hours a day, sitting on the porcelain throne and never read and digest all the thoughts thrown at me. Most of it, just recycled crap, with different adjectives, adverbs, and nouns to describe the people and groups they were taught to dislike.

But, I am always in the hunt for newer and better computer software and hardware.

I think Unqualified Offerings' previous piece (Physics vs. Biology: Career Edition) captures that from the student-view.

Working on the assumption that our market economy does reward the "important" ...

I've said before that public institutions would do a great service if they'd just survey their past graduates for income. If physics majors are all making $200K, even if they aren't in physics anymore, it's probably worth keeping a big program. If theatre arts majors are making $12K a year, maybe that's the one to cut.

(My perspective as a Chem BS, who got out of chemistry, into computers, and did ok.)

The emphasis in most administrations has been on education rather than on creating jobs that educated people might hold (other than in government itself, of course). Wrongly, in my view.