Having stopped consuming processed sugar a few years ago, I can easily say this was the single change I've made with the largest impact on my health and quality of life.

When I started reading labels and stopped buying anything with sugar, corn syrup, evaporated cane juice etc., I automatically eliminated processed food.

As for food companies, their responsibility is to maximize profit which usually involves selling as much as possible at the highest profit margin possible.

Given that high profit margin excludes the possibility of expensive quality ingredients, the variables that remain are taste and perception. Thus, food commercials, stories, "healthy food fetishism" (and pushing same crap as such) and taste laboratories where scientists focus on making said crap palatable, tasty and if possible addictive.

Sugar is an addictive substance so it is almost always a part of this formula.