1. It allowed people to settle in one location and build the first cities because they no longer were forced to migrate with the food sources.
2. It allows people to pursue vocations other than farming. Without agriculture and the advancements of modern agriculture, then we would have fewer doctors, lawyers, scientists, factory workers etc etc, because those people would have to spend their time gathering their own food.
3. It provides a higher quality meal which has improved the health of everyone.
4. It provides a major source of export trade which allows that country to use that money to expand.
5. It provides multiple benefits besides just food, for example clothing and medicine.