Cake decorating is fun, the sugars are used so that you can frost boring cakes, making them be more pleasing to the eye.
I don't know the first thing about cake decorating!  How does a person even learn how to do that?
Well, there are many classes, but it was first said to be created by a French bakery back in the 1840s. The bakery wanted to get more money for their cakes so they decided to decorate to make the price increase seem worthwhile.