This is still generally argued back and forth. Some people point to the effects of the New Deal that were already starting to revive the economy as evidence that the U.S. didn't need the war production, and that the war production itself was an extension of aspects of the New Deal (such as the Civilian Construction Corp). Further, without aspects of Roosevelt's policies improving working conditions, it's unlikely that war production would have had the drastic effects that it did.

The rationing had much more to do with saving scarce commodities like rubber, tin, nylon, gasoline, and fuel oil for the war effort, as well as helping to counteract the effects of U-boat raiding (in the case of coffee, sugar, and rubber here, as well, since synthetic rubber tires were a ways off).