Does Grad School ALWAYS Improve Job Prospects?

The mantra for years has been that more education equals more opportunities. But is this always true? Part of it depends on the type of education. The link here is to an article in The Chronicle of Higher Education that challenges the value of graduate degrees in the Humanities. It's one thing to go for a certification in your current line of work, or to study for a specialized technical skill. But that Masters degree in History or English, while intellectually stimulating, may leave you deeper in debt down the road, with no more career prospects.