This. Nescafe was great for the same reason, as it weighed much less than coffee grounds.
It's impossible to overestimate how important this was. The U.S. military in WWII had to support an enormous force overseas, to a degree and extent that no other power had to approach. Everything that the force needed in the field had to first go on a ship to be sent overseas. With the U.S. Twelfth Army Group numbering over a million men alone in Europe, small changes to products were magnified at scale, saving tons of weight in the logistics chain.
It's also worth noting that WW2 by and large predates intermodal shipping containers. Apart from some experiments late in the war, the U.S. military did not use containerized shipping to any significant degree. Everything was shipped "break-bulk" which meant that every individual parcel had to be loaded/unloaded by hand every time it changed transportation mode. Also, the ships that carried these goods were tiny by modern standards. Every bit of extra volume and weight mattered much more than it does today.
There's a probably apocryphal story that a Japanese higher-up realized the war was lost when they found out the US had enough spare capacity to build ice cream ships for in-theater cold treats (https://en.wikipedia.org/wiki/Ice_cream_barge).
Probably apocryphal, but I'm sure there were similar conversations. Though from what I've read, many in the Japanese High Command were fully aware of the disparity in war-making potential between the U.S. and Japan. That Japan decided to go to war anyways despite knowing this is still discussed.
There's a page over on combinedfleet.com (great resource and discussion) that goes into the numbers, and it's truly astonishing. U.S. output could be described as terrifying. http://www.combinedfleet.com/economic.htm
It's impossible to overestimate how important this was. The U.S. military in WWII had to support an enormous force overseas, to a degree and extent that no other power had to approach. Everything that the force needed in the field had to first go on a ship to be sent overseas. With the U.S. Twelfth Army Group numbering over a million men alone in Europe, small changes to products were magnified at scale, saving tons of weight in the logistics chain.