Recipes are important instructions for a consistent result. Even though cooking is art, a good recipe makes a difference between a delicious birthday cake and a disaster. For consistent results, it is important to follow recipes.
One of the key elements provided by recipes is proportion. Even when you know basic ingredients, a recipe has the right ratio between them. Professional cooks who make recipes know how much milk should be added to a certain amount of flour. Without the right balance of ingredients, you can end up with useless masses of dough instead of waffle batter.
An amateur cook can create a delicious sauce, but it wouldn't be possible to duplicate without a recipe. Recipes provide all the elements necessary to reproduce food without fail. Cooks can change something, but the basic recipes will always deliver desired outcomes. Recipes also include temperature settings, cooking times and serving instructions.
There are situations in which recipes aren't necessary, but until you gain enough cooking experience, recipes are your key to success.