People from my generation aren’t buying Calbee because the bag is colorful. They’re buying it because it’s Calbee and they already know what they’re getting. The packaging could be black and white and I’d still recognize it instantly.
The only people I could see being briefly confused are younger consumers. Japanese packaging tends to be very colorful, so we’re all conditioned to identify products partly by color. But people adapt quickly. In fact, a black-and-white Calbee bag might end up standing out more on a crowded supermarket shelf than yet another brightly colored package.
There’s also a chance this ends up being a net positive. If simpler packaging lowers costs and sales stay the same, why go back? Japanese consumers are feeling inflation more than they have in decades, and companies are under pressure too. Cutting costs in a place customers barely notice seems a lot smarter than shrinking the product or raising prices again.