In the case of the cake without eggs, the story goes like this. A company invents cake mix but find it's not selling very well. A salesman and psychologist, recognized for the first focus group (probably another lie), Ernest Dichter decides to poll women as to why they don't like baking with the cake mix which is arguably better tasting and easier to make. After all, you just pour the box into a bowl and add water, right?
But what Dichter (supposedly) found was that the recipe was too easy (everything including eggs was included in a dehydrated mix). Women didn't feel like it was their cake, there was no pride in their creativity. Perhaps it was a bit of resentment towards Betty Crocker that their husbands loved her cooking more than theirs? So the moral of the story was that the cake mix company decided to add eggs to the recipe allowing the women to feel like they were participating in the baking process and making a "recipe" rather than a mix. Why are so many instructions on pre-packaged foods providing alternative preparation methods? Perhaps it's because of the tale of the cake with no eggs?
Indeed, according to the magazine Bon Apetit, women generally state they've made their cake from scratch even if it comes from a box.
So what's the take-away? Give your audience options. Give them ownership in the process and make sure you understand how your product emotionally affects the psychological relationship of the environment it's going to be placed in. A tall order for sure, but if you want your cake and to eat it too then you have to crack an egg to find out what's on the inside.