Japanese packaged food is so good because it is typically prepared seasonally, or onsite, so you’re getting fresh ingredients. Another reason is the packaging often “maintains the integrity of the ingredients”. For example, an Onigiri is “a seaweed wrapper encasing a packed handful of rice stuffed with a savory filling.”
Sounds simple enough, yet the packaging separates the nori (seaweed) and the rice — they only touch right before you eat the onigiri”. Even the packaging of snack foods is “often exquisite and elegant. Special care is taken to ensure that shapes, colors and designs fit perfectly in a symphony of tastes and textures”.