This sort of accident seems to happen all too often. *I don't recall
anything in the private licensing curricula about horizonless night
flight hazards. *Perhaps it got overlooked, and it's time the FAA took
steps to include it in pilot training.

Actually that is covered in PPL training. In particular the "Airplane
Flying Handbook" covers the many of the nighttime hazaards.

It's also covered in the checkride but only orally.

I wonder if Denny might enlighten us about what non-pilot profession
gets his thumbs up as far as accident rates go. If the Bonanza and
Cirrus are popularly referred to as "Doctor Killers", then I guess 30
year old C150s and C152s must be the "Average Working Stiff Killers".
Or maybe doctors and lawyers lead the charge there too?