There are many benefits of food plots. I've been planting them for 23 years, ever since i was at a pasture walk and saw the benefits of grazing turnips by cattle. If your trying to grow big deer, there are nutrition benefits of brassicas and some of the improved varieties of clovers over alfalfa and other legumes. Food plots also extend the grazing season. There are also huge mineral/nutrition benefits of some food plot products. In areas where baiting, minerals are prohibited in Wisconsin, you really can help rack development by proper selection of food plot products.
Plus, when you plant food plots, it also can be a relaxing hobby and learning experience. If it's fun, then look at it as a nice hobby.