I have not read this book so I am responding your discussion.
In it he laments how this book has always remained more popular than his later creations and, despite being first written in 1976, it has not become severely outmoded ans superseded.
I would agree thay it is a shame that there's not more criticism for this book but I don't rhink it's from a lack of scientific evidence. The concept of a "spirit" or "soul" is a cognitive construct and although it has taken a while to get the technology right to do so, we can now observe how the brain works in real time and have solid enough understanding to give very reasonable explanations for any "spirit" phenomena like near-death experiences.
The fact that these discoveries are suppressed is due to a religious mindset that demands belief beyond evidence. Just as we understand that people that came before us believed foolish claims like thunder was the gods fighting, we appreciate that the unknown has a "magical" quality, but we must strive to always be challenging our beliefs in the face of well-controlled, repeatable scientific evidence.