What has he done for the food industry?
Nothing. So why do we even have him around? The reason Wario was born was to endorse delicious garlic. Of course, Nintendo decided to give Wario his own series of garlic based condiments which were awesome until they decided to give him that line of herbs and spices with hints of cayanne, but that's not my main point.
Outside of school cafeterias, Waluigi has not been in any major kitchens. If he won't deep fry delicious food, why bother keeping him? He is worthless and just there for the sake of there being an evil, less culinary experienced clone of Luigi.