I'm surprised a car buff like you doesn't understand how the grille is one of the most identifiable parts of the car. The grille of the car is part of brand image for many manufacturers and has been for many years.
BMW and the kidneys, Mitsu and it's Lancer inspired full face grill, Audi, Lexus, and so many others all use the grille as one of the most unique and distinguishing part of their cars.
Maybe I'm wrong about that but being opinion and all, I'm sticking to it. The grille is hugely important and Ford has been wearing that Aston grille way too much for my taste.
That said, I can't blame manufacturers for using the grille as their primary means of differentiation from other makers, after all, the shapes and styles are becoming more and more bland while more and more similar with every new year.