I recall travelling on a Trident LHR~HAM in December 1975 that had an experiment with a few rows of rear facing seats at the front of the Y cabin. At check-in, I was asked if I would sit there and fill in the questionnaire. Naturally I did and it was all very comfortable.
My guess as to why they have never made them standard around the world is that, they would have to tell folks that it is safer that way in an emergency stop or incident. THEN they would have to explain to folks why they had not reversed the seating years ago!
