Suppose we were able to cure all disease at this very moment. All of the people who would ordinarily die will now remain alive, resulting in a higher-than-usual population. This effect will only be further compounded by those people who would have died now being capable of having [more] children. However, you may have noticed this problem isn't strictly limited to disease. Any mechanism, tangible or not, which prolongs the life of someone who would otherwise die, will in effect produce a higher-than-normal population. So, while saving people sounds good on paper, the inevitable result is an increased population and its subsequent effects (eg. overpopulation resulting in famine, crime, etc...). What is your solution to the problem?