Notice how we do this with everything now, we flatten things out to save space. It's the same reason people fold their clothes a certain way for packing or buy those vacuum seal bags for storing winter blankets. Once you realize flat stacks take up way less room than bulky piles, it changes how you look at your whole kitchen. Freezing rice in a flat bag is just that same trick applied to food. You get faster thawing too since it spreads out thin. It's one of those small things that makes you wonder why it took so long to catch on.