Why do we need catastrophe?

Just finished watching Blood Diamond, and was thoroughly impressed. Despite it's hollywood trappings (tragic heroism, sacrifice, a showdown, a reunion, a final goodbye, hope...), it was very watchable, though uneasily at times. Looking at some brief reviews, I'm often struck by reactions to politics and activism in film, though I'm sure it depends on the reviewer, there is a tendancy to look for entertainment and artistic value first, which is fine, but tends to overlook or ignore questions like why not have an agenda as a filmmaker? and why not cram in a message?
Whether it's global warming, conflict diamonds in Africa, corporations, or scandal, there is often a defensive posture, a leaning-away-from. Indeed, many issues are far larger than any one person can do much about, but in looking at (or looking away from) the biggest events, the small things are missed; small things like personal responsibility and choice, discipline and awareness. People are dying for diamonds, yes, why do we need diamonds at all, each of us? The environment is being degraded or changed, or ruined, why must we drive so much anyway? Why do we, I, need a catastrophe before I realize that the small things I do have consequences, and the small things we all do have big consequences? I have a choice despite what is all around, and there is so much good that can be done in small actions. Let's make a list.