Look, I realize that Denethor is not, strictly speaking, a nice person, and that he is a pretty lousy father to Faramir, and that he is being driven slowly insane.
He is still the steward of Gondor, and he knows which fork to use. He can eat tomatoes without spilling them all over his chin. He does not eat meat with his fingers. He probably does not speak with his mouth full.
The men of Númenor did not sail from the West and establish kingdoms so that Denethor could make fruit explode. The blood of Númenor does not run in his veins so that he can eat like an animal.
Come on, Peter Jackson. I realize that terms like "subtlety" are foreign to you, but could you try to pay attention to terms like "characterization?"