While I don't really disagree with your first part (the website really seems to be a bit in poor taste), categorizing death as a disease seems a rather strange thought. I really do hope we never have to discuss the ethical and moral (let alone societal) implications of people being able to live forever; life's finiteness might not be something we should celebrate, but it does have its benefits.

Death is the price our species pay for evolution. It also brings change, which sometimes allows the situation to improve. If humans didn't die, dictators like Stalin or Mao would rule indefinitely long. Hell, humanity could still be enslaved to some powerful Pharaoh, who would see little incentive to change things, being immortal living god, and his power would not erode on an inevitable succession.