The Assassination of Jesse James by the Coward Robert Ford: Why America treats thieves and murderers as heroes?

It's been ages since I saw this film. Time is the best test on a film's quality. If after some months a film has still a intense impression on you then it had something to offer. On the other hand, if it has faded away completely it wasn't worth seeing in the first place.
The only thing that I remember from "The Assassination of Jesse James by the Coward Robert Ford” is a golden atmosphere and good acting from the leading actors.
In Greece it got rather enthusiastic reviews and some were even saying that it managed to renew the genre of western. But was it really a western? Instead of gun shooting and action scenes the film relied mostly on scenes that explained the tensions and the relationships between the characters. Its’ pace was slow. The shots were majestic in an effort to resemble Fords masterpieces. The acting was intense. Still the film didn't manage to over pass the level of mediocre-acceptable.
The story is already known to most western funs or American history lovers. The strong elusive thief Jesse James is betrayed and killed by one of his own Robert Ford. It has been presented in film over and over again. It had its appeal when we were children. In this film a story that is a teenage (at the most) action story is supposedly presented in an adult way. And that is the problem. We are supposed to be taken in by the tragedy and the drama of the life and death of Jesse James and see him as a hero. Is that possible for a healthy adult? How can one seriously identify with a thief and a murderer? Of course most of us can identify with James Bond or with Ocean's group of thieves. In these examples, though, we are never encouraged to take the films seriously. We are there just for the fun. We indulge in a fantasy world where everything is sparkling and ingenious and we can even be above the rules of society. Sometimes we have (for example the Bond films) the limp moral justification that we are fighting against evil. Other times we are thieving just because we are clever enough (thieving is not as bad as murder in any case). In the Assassination of Jesse James by the Coward Robert Ford though the story is supposed to be taken seriously. The realistic scenes, the great acting, everything in the film leads us into taking a serious adult stand towards the story. Then the film presents murderers as heroes and tries to introduce us to a code of honour that is above society and human life. How can this work? Unfortunately American history and culture has learned to glorify a code of honour between men that justifies murder (if there is a proper moral cause or if it is against some Other or if the murder is clever enough to remain uncaught and become famous). Why though should we accept this unchallenged.
The Assassination of Jesse James by the Coward Robert Ford is a well executed technically film. It is an attractive package with a problematic soul.