That's an excellent film clip and I hope it gets a lot of play on TCM, one of my favorite channels. You hit the nail when you said that the classic western is about heroes, about ordinary people caught up in something extraordinary and they've got to stand up and do what's right. Where did that ethic go? It's been a long time since I've seen a modern movie so simply and honestly follow that plot formula.
As for Stagecoach being the Citizen Kane of Westerns, that's a toughie. You'll get more lists based on individual tastes. I tend to agreed with you, though, when I think about the cinematography, the use of shadows and light, as Orson Wells did in his masterpiece. The landscape, the variety of characters, the strength of the acting. The modern version is a sad adaptation of it, truly anemic for all its technicolor. And of course, John Wayne grabbed your attention from that very first scene and never let go. What a powerful reintroduction of this wonderful actor. (Remember The Great Wagon Trail of a decade earlier?)