A shopper decides whether to pick up a product within a couple of seconds. That's usually before reading a single word on the label. Packaging that looks cheap makes the product feel cheap, whatever is actually inside the box. Packaging that looks premium earns a second look. That's true even from a shopper who has never heard of your brand before. On a crowded shelf next to a dozen competitors, that split-second impression matters enormously. It often decides whether a product gets picked up at all.
Good packaging design also has to survive contact with the real world of printing. Colours look different on screen than they do on an actual printed box. A design has to account for die lines, fold marks and the material it prints on. Otherwise it simply will not translate correctly to production. We design with those production realities in mind from the start. What you approve on screen is genuinely what arrives on the shelf.