I never thought of this before but I think that some of this discussion about reclining is an unintended consequence of getting rid of meals when the tray use meant that the seats had to be left in an upright position for a substantially longer period of time and it gave people something to do and be slightly more sociable so that they werent immediately looking to go to sleep.
Also, back then the entertainment was on a projected screen in the front, or later on monitors suspended from the ceilings. It's only recently that personal screens are built into the seat backs, creating another conflict in the recline vs. screen view.
And as technology marches on, even the seat-back screens are making way to personal tablets and smartphones, where the airlines can simultaneously outsource the monitors to the passengers and charge them for the wifi access to movies.
All in all, it's just another brick in the wall of irritability.
-PJ