Because we react strongly to exaggeration:
Baby chicks presented with parents with exaggerated versions of the features they’re homing in on — the color of a parent’s beak, say — will respond more strongly to an exaggerated, but artificial, version of their parent than to the real thing. In the same way, humans home in on versions of reality in which the most enticing features are enhanced. In food, that’s texture, color, and anything else we associate with nutrient density, mouth feel and general deliciousness.
The Dish 