When the U.S. entered that war in 1917, Europe had already been fighting it for 3 long, dreary, and sickeningly brutal years. Despite America's seemingly steadfast neutrality, Germany's provocative actions made our entry into the conflict nothing short of inevitable.
For that matter, why were they so important to the government at that time? Hard as it is to imagine today, during the First World War, the United States was short of nearly everything it would need to fight. Citizens were asked to donate any weapons, horses, and ammunition they possessed to help supply the army. Rationing was also very much in vogue, to feed the troops and everyone on the home front, as well as to help relieve famine in Europe. Concepts such as "Meatless Mondays" and "Wheatless Wednesdays" were implemented to help the food rationing effort.
And when you think about it, they still are. A nation that uses its resources wisely and supports healthy lifestyles in its citizens, ensuring safe and nutritious food, is far better equipped to handle the threats of the future than a nation that does not.