While studying for my Masters degree in technical communication (English), our graduate professors constantly harped about their jobs. They consistently told us that if we wanted to pursue a Ph.D. that we should consider the unglamorous life of a college professor where summers are unpaid, tenure is difficult to get, and asskissing is the only way to get ahead.
I had no desire to go any further in my education. Ph.D. is a Doctor of Philosophy in the respective discipline. Doctor, in this sense, means “teacher,” and I had no desire teaching mushbrained 20-somethings how unfair the real world really is.
Not to mention the huge chunks of time it takes to read, correct, and grade written work.
If you gotta teach, much better to choose a discipline that lends itself to multiple choice.