Why do so many books in Japanese consist of transcribed interviews?

They are quick and cheap to produce (important when, as in many Japanese markets, extreme trends quickly come and go), demand little skill from the editor (important when, as in many industries, editorial staff are generalists with unrelated degrees who could just as easily have ended up in the HR department at the end of their new recruit training period), are easy to read (important when literary Japanese is still almost unreadable to the average tired salaryman), and avoid all kinds of risk- especially the risk of misquoting someone