I think you've mostly got it right, although I didn't do the best job of communicating it. At first I was just pondering the idea that utilitarianism seems to support martyrdom if you're going to die anyway, but I realized that the theory actually applies to any finite lifespan. If we lived forever, the marginal utility of our lives would theoretically increase ad infinitum - we could bring more and more learning and experience to each problem we face.

However, until that happy day when nobody has to die anymore, thinking of death as an act (something you can use) instead of an act of god (something you take out insurance for) might help altruistic causes. This also might be a good attitude for soldiers to take (or one they already take, but not being a soldier, I wouldn't know).

It also, I think, helps me as a person to think of dying as something I do - it makes me feel more in control of my life, rather than just living with a scythe over my head that may come falling down at any moment.