Maybe food could be used for an end-game score? How good of a feast you could make at the end of the game? (Note: not entirely a real suggestion, just some musing.)
That is a neat idea on its surface, and it holds value as one option that has not been brought up yet. However, I can't think of an rpg that implemented a scoring system, and I don't think it would be fun to do so either, especially if it was centered around something as mundane as acquiring food. Traditionally scores are implemented to act as the driving force behind a game, an rpg accomplishes this through quests. The closest thing I can associate scores with are trophies for defeating particularly difficult monsters, and the value there is to brag about it to other people in an mmorpg. In a single player rpg, trophies are either connected to a quest, or they are a neat afterthought after achieving something more difficult.
I'd associate it with more like, Riddler Trophies in Batman games, Street Tags in GTA: San Andreas, or other collectables in other games. I don't necessarily think it's a great mechanic, but I was just trying to think of ways to keep the food without making it critical.