In Vanilla: The Cultural History of the World's Favorite Flavor and Fragrance by Patricia Rain, there is an argument that Vanilla was used as a cover flavor for a lot of health foods. Vanilla has a very strong flavor and can be used to over power others. Since vanilla was used so prominently many people began to see the flavor as plain. There is also an argument that Ice Cream was often accompanied by fruit or was fruit flavored. Having a plain white non fruit flavored ice cream would be considered boring.