Of the four possible reasons he suggests, I suspect the third is the primary reason, though I wouldn't go so far as to call it the "third rail." I don't think dealing with such questions will kill your career, but it won't get you anywhere either. Connor writes:
Senior colleagues don’t encourage it; professional journals don’t publish
it; deans don’t reward it and a half dozen disgruntled students might sink your
tenure case with their teaching evaluations.
While there are no rewards, I'm not sure that dealing with "Big Questions" is likely to leave one with disgruntled students. Connor's own research suggests that the students aren't the problem -- all the professors and administrators are:
But there was wide agreement that other big questions, the ones about meaning,
value, moral and civic responsibility, were in eclipse. To be sure, some
individual faculty members addressed them, and when they did, students responded
powerfully. In fact, in a recent Teagle-sponsored meeting on a related topic,
participants kept using words such as “hungry,” “thirsty,” and “parched” to
describe students’ eagerness to find ways in the curriculum, or outside it, to
address these questions.
I think this thirst is very real, as I mentioned here. And I try to deal with the Big Questions in class. For the most part students respond well, and why not? When you are nineteen years old, there seems to be no reason to learn the plotline and major characters of The Odyssey -- but the need to understand Telemakhos's struggle to learn "What does it mean to be a man?" seems pressing indeed. They are often moved when they learn that the answer Homer gives is that a real man leaves the sex nymph behind and returns home to his wife and kids.