Why were consumer goods rationed during the war?
To pay for militarise debt for world war 2
They had to ration them, there was not enough goods. If they had not rationed it then businesses would have driven up prices. And to make it fair to everyone and prevent cost rises they rationed them. The rest of the goods were needed for the war. because there wasn't much! Because the military had first choice.
You need to specify a country and a time. There's a widespread misconception that specific goods were simply either rationed or not rationed and that the amount(s) allowed then remained constant throughout the war. The tendency in all coutries was for more and more things to be rationed, and for the amounts allowed to be reduced. In Britain, for example, bread was not rationed during World War 2, only afterwards!
Goods may be rationed during wartime for a couple of reasons. When commodities become scarce (which can happen during wartime) and demand remains the same prices will rise, maybe a lot. Rationing reduces the demand and thus keeps prices from going out of reach for ordinary income people. Some commodities such as tires, gasoline, etc. are needed for the war effort, rationing makes them available for this purpose. I don't remember services being rationed but…