I was watching the World at War the other day and it was saying that Churchill's drive to collect people's domestic scrap metal (saucepans etc) was purely a psychological operation. The stuff had no military value, it wasn't melted down to make armaments of any kind. It was just something to make the whole of society feel they were doing something and being involved.
My dad tells a story of how his entire town gathered in the town hall and was invited to buy war savings stamps and stick them on a bomb that would then be dropped on a German city. This was a double win for the government since not only were people lending it money by purchasing the stamps, but by instantly throwing them away they were guaranteeing that they would never seek to call in the loan.
After the war the 'bomb' was discovered hidden in a cellar. It wasn't really a bomb, of course, but a clever propaganda-cum-financial device.
And, let's not forget, tricks like this helped to defeat Nazism, so they were worth it, no question.