I ask myself often when buying Lego why the boxes are so much bigger than the space that is needed for the contained content. It seems a waste in terms of material and logistics. I do store the boxes and especially the bigger sets needs lot of space in my appartment. I would be happy to have them smaller.
The possible reasons include:
- Surface area needed for legal info, practical requirements like barcodes, information, feature descriptions and artwork
- Aspect ratio of the artwork means the boxes can't be too long and thin
- Leaving space between the bricks so they don't get squished up against each other
- Size of the instruction manual or sticker sheet
- Psychological tool to increase the perceived value of the set
- Larger boxes grab the attention of the consumer better
- Larger packages are harder to steal
But the exact reason is likely a combination of some of the above ones and maybe some others, most probably in a top-secret ratio known only by LEGO.