It isn't that they die - it is that they die before they can realize many of their dreams, before they can change the world in the way they have been working towards, before they're done.

We hate cancer because it takes from us those who wish to give so much without consideration. An indiscriminate killer that wastes our treasures away before our eyes, leaving us with only memories, partially realized dreams and the rage of "why now, when there was so much more good to be done?!"