Though note it was primarily the invention of artificial vanilla substitutes that made vanilla seem cheap/attainable. (Real Bourbon vanilla from Madagascar, for instance, is still far more expensive than most people realize.) There may even be a larger useful metaphor there, too, that "plain" vanilla is most often "fake vanilla".

Lots of dessert / ice cream recipes use vanilla as an ingredient regardless of what the final flavor is meant to be. This also leads to the vanilla === plain misconception, imo.