I can't think of an evolutionary advantage of desiring variety, it seems (although I don't know if there is any studies to the effect that it is true) typical that various fauna have a 'typical' diet that they forage for and rarely vary. Even omnivores who are able to forage on a non-seasonally variable food stock.
From an economics point of view, as a single eater, having a limited variability, allows bulk purchases to take advantage of the economics of scale and reduces landfill waste (fewer containers overall).