The development of processed foods in the U.S. is closely tied to the military. They funded research into more shelf-stable foods like "cheese product" and preservative laden bread. Manufacturers appreciate their products expiring more slowly as it helps out their logistics. It's not really anyone's goal to feed us all stabilizers and preservative, but because it's cheaper for big companies it's what we get. There's not much in the way of consumer protection in this area.
Certainly there's good chocolate, but price is a major factor at the grocery store. A big Hershey bar (the size of your hand) is $2 and a similarly-sized bar from a better manufacturer is at least $5.