Mahogany, I don't think it's necessary to be so smug and dismissive of other people's opinions. And as you've spent time on these boards I'm sure you realize that people here did not see BBM just "to see 2 guys doing it." I do agree with you about Jack dying in an accident but it really isn't necessary to know what happened. What matters is that Ennis believed he was killed, which only reinforced the fears he'd had all those years. That was part of his tragedy, that he was a prisoner of his own fears. For good reason, to be sure. The event from his childhood was a chilling one and the way he was raised cemented his fears and his own homophobia. The other part of his tragedy was that he didn't fully understand what they had and the depth of their feelings for each other until Jack was dead and it was too late to do anything about it.
As to why Randall wasn't killed (so I stay on topic) I think people over-think this whole piece of the story. Again, either Jack was killed or he died in an accident. If he was killed it doesn't matter who did it or why. The important thing is that Ennis believed he was killed. The details aren't relevant to his story and it's very much Ennis' story at that point.
Twister is right that this story is about homophobia and the effect it can have on people's lives and happiness. I'm not sure I'd say the characters are secondary because without specific characters to relate to and care about, we wouldn't feel the impact of that homophobia or care about it. Hopefully the biggest thing people got from this story is the recognition that it's about two human beings who want and feel the same things everyone does. And maybe that will make us treat one another a little better. Even if we think of some people as different than us.
Just a quick note about Annie Proulx. She did make that remark but it was in a passing moment of irritation and frustration with particular people who had insulted her work with the notion that they could 'improve' on it by giving them a happy ending and sent her manuscripts that were little more than soft core porn as examples of their 'fix' to her work. She has actually said many positive things about it since then and participated heavily in the opera, as well as other BBM related projects. I'm glad to see that bump in the road didn't leave a permanent bad taste in her mouth. She created something quite beautiful and I'm glad she shared it with the world.