Late to the party, just discovered this sub.

One thing I don't see mentioned in this thread, on top of all the other stuff that's been going on, is ongoing soil depletion / degradation / loss-of-mineralization in the last 50 years. This makes all food plants (for our herbivorous food animals or indeed ourselfs) horrifically less nutritious. It's an ongoing irreversable trend as long as humans keep growing in numbers. There's plenty of charts articles and videos to find on this. To give you an idea, to get the micronutrition (the stuff beyond the sugars and the water) from a say 1950s, 1960s apple or kale or whatever, you'd have to eat dozens.

I believe this is related to your query as more nourishing food is more flavourful --- else it would all taste like water-and-sugar.

Seeing color movies of the 60s and early 70s I'm blown away at the "glowing skin" of most. Roles you wouldn't ever make-up for, such as dusty bandits or frail old preachers etc. Hyperactively-aware eye movements and such --- would think such folks on drugs nowadays. Bodies just radiating strength and energy in a way that can't be acted, even in roles that utterly don't call for it, and that I recall in few people from my mid-late-80s childhood and never see today. Really hard to explain, too. Probably futile anyway. Soils are slowly going the way of the dodo, which means we're more and more growing the equivalent of cardboard in terms of micronutrition and flavour.