Eating less is not the same as less calories. Fresh vegetables have more micro-nutrients than most food, but they lack carbohydrates and complete proteins necessary for completing amino acid chains. However, eating a variety of vegetables can provide for various amine groups from protein sources - providing the ability to make complete proteins.
It also depends on your body type. An endomorph can eat 200% less calories than an ectomorph, and gain 4x as much weight. A mesomorph or athlete may need 5000 Cal - 10,000 Cal a day. When I was training, I had to eat every two hours. My daily caloric intake was 8500 cal/day, and I couldn't keep weight on (mainly due to my training). I also drank about 2 gal of fluids a day (not including food). When I was training, I got most of my protein from lean meat, but I had to force myself to eat the meat because I am generally vegetarian.
However, I would say that I know what you mean. It is true eating less in quantity can improve digestion. But, I would disagree that better food availability and price is mitigated by the quantity of food needed. Layperson don't know this, and aren't given access to much information that wouldn't cause them to diet and destroy their metabolism. The people who would have access to this type of information have the means to buy the "heirloom" vegetables and non-hormone/non-antibiotic/grass-fed/free range/glatt/kosher (LA) food.
Nutrition is a class, social and psychological issue now. It used to be the "rich" were too ignorant to realize what they thought was trash food was actually the most nutritious. Their epicure blinded them from nutrition. Now, they are eating those foods, and convincing laypersons to eat the trash.