Some good films do get forgotten, unfortunately. That doesn't diminish their quality, nor does it diminish Art Carney's superb performance one bit.
Agreed that Godfather 2 & Chinatown are excellent films, deserving of all their praise, no question about it. But their lead performances are those of bold, striking characters amidst a memorable & violent background few that people actually experience themselves.
Harry and Tonto is a more humane & humane film, about people we might know, people we might be ourselves—the smaller, quieter sort of film that says a lot without any fanfare or sensationalism. And Art Carney delivers an emotionally rich, contemplative performance that has a great deal to say about growing older & how to face it—and that's something each & every one of us must face eventually. It strikes closer to home for everyone. And that sort of film & performance demands more of us, not just as viewers, but as human beings.