Right, the furnaces aren't used to bake cookies, they are used to melt metal. Someone from the "Military-Industrial Complex" needs a furnace to melt metal to manufacture artillery shells or whatever. He remembers these two big furnaces, so he writes a letter to the head of the Atomic Energy Commission asking if he can use them. The AEC guy checks with Saddam and responds, saying the military guy can use the furnaces.
I always try to think like "the opposition" when reading any of these letters, and these two can be viewed as completely innocent. One explanation of these letters is that since the furnaces were no longer able to be used for a nuclear weapons program due to UN sanctions, they were reallocated to the Iraqi military to assist in manufacturing conventional weapons. And that's probably why these letters won't show up in any MSM stories either. But they do add to a nice overall body of evidence.
Also the Degussa furnaces were not going to support a major industrial output like melting metals to manufacture hundred if not thousands of shells that Iraqi Army needs. In fact the Iraqis were manufacturing or importing these shells and not depending on any Degussa furnace to be part of the production effort.