Given human propensity for self-inducing death
We certainly don't need it to thin the herd.
Why does nature need for cells to decrease in function until there is seizure?
Perpetual existence would seem to be a better choice given the amount of energy that goes into procreation/rearing.
The reason for age, is so we have a reason to try. Because, if you had forever, procrastination is much more a convenience.
So, maybe we need the prospect of an impending end to drive is to reach such that we might attain within the amount of time we have.
The concept of time itself, I would argue, is a result of a society's preoccupation with death (avoiding it).
Without aging(-->death), we are the Eloi,