Even the director questions whether it was all that great:

In a 2015 interview, Paul Haggis commented: "Was [Crash] the best film of the year? I don't think so. There were great films that year. Good Night, and Good Luck – amazing film. Capote – terrific film. Ang Lee's Brokeback Mountain, great film. And Spielberg's Munich. I mean please, what a year. Crash, for some reason, affected people, it touched people. And you can't judge these films like that. I'm very glad to have those Oscars. They're lovely things. But you shouldn't ask me what the best film of the year was because I wouldn't be voting for Crash, only because I saw the artistry that was in the other films. Now however, for some reason that's the film that touched people the most that year. So I guess that's what they voted for, something that really touched them. And I'm very proud of the fact that Crash does touch you. People still come up to me more than any of my films and say: 'That film just changed my life.' I've heard that dozens and dozens and dozens of times. So it did its job there. I mean, I knew it was the social experiment that I wanted, so I think it's a really good social experiment. Is it a great film? I don't know".