Also he physically can't take it off. It doesn't come off. The things that were done to him -- biologically and psychologically -- created a vast gulf between those he fights for.
He's not supposed to be relatable because he's not relatable, that's the entire point of his character. John's arc in the games: "coming to terms with your humanity after war has changed you into something unrecognizable"
John's arc in the show: "lol. lmao."