In 1966, 86 percent of college freshmen said that developing a meaningful philosophy of life was essential or very important. Today, less than half say a meaningful philosophy of life is that important.
My first thought was that today's faculty are much less likely to believe that they are supposed to help students develop a meaningful philosophy of life than were the '60s faculty. True, there are particular egalitarian and environmental values which are often presumed by many faculty members. But it has been my experience that most professor balk at the idea of articulating a meaningful philosophy of life for themselves, much less seeing their job as helping students do the same.
I can't speak for the the faculty norms of the '60s. I do infer from the fact that the question seemed intelligible when the survey was created that it seemed like a sensible idea at the time.
Brooks cautiously concludes from the above facts that "I’m not sure if students really are ... less interested in having meaning in their lives, but it has become more socially acceptable to present yourself that way."
I think it likely that a big part of this change is that college faculty are less likely today to see "helping students find a meaningful philosophy of life" as their job, or even within their competence.