That's good for achieving the 'over 90' award, if you have a decently robust population. The basic idea is that 'over 90' isn't something you achieve, it's just something that happens when it's ready to.

For general worries about ailing villagers, though, leaving them alone doesn't help them live longer. It's all in keeping plenty of healers, a hot fire, and restoring those who are seriously weakened with potions.