Maybe the reason is that a large number of the people who are dying today are already on borrowed time. Consider this as an option, just for a moment. The medical advancements in the last 100 years increased the survival chances of many who would not be here already, if not said advancements. Natural selection exists for a reason. We, as a species, are actively working against natural selection, definitely on the medical front.
Thus what we are maybe witnessing today is a natural selection in action.