Good question you got there mate.
For me saving lives should never be something that's forsaken, Human life is precious after all. I mean what happens if the person that's supposed to figure out how to save the world ft over population dies because we decided to stop figuring out how to save lives.
Regardless of the threat of overpopulation, saving lives should always remain important because each life has value and an illness or an accident shouldn't be a death sentence for anyone.
On the other hand, if you talk about prolonging human life, as in extending the life expectancy of human beings then I truly believe that's a bad idea because the earth can only support so many lives. On the long run I feel overpopulation will be what gives humanity its final blow, not an apocalypse or a meteor so I fully understand your point.
The thing is that to stop trying to save lives would most likely still lead to extinction because the reason why humans have lived this long is because we're constantly looking for ways to fight things that hurt us, things like Ebola, HiV etc and without people to stop them then humanity might not have gotten this far.
I hope this helps.
I think it is a good thing.
How good is humanity in general at such things? Suffice to say we still have room for innovation.
The Struggle is harsh enough - we might as well allocate some of our own time (or, as a society, allocate competent/talented humans) to enthusiastically probe that topic.
As a Homeopath, I spend some of my time analyzing health problems and making recommendations to optimize the probability of desired outcomes. These efforts have thus far been "good" for all parties involved.