In our modern era I think most would benefit from having a healthier relationship with death as well. Death is inevitable to us all but modern life shields us from much of this. I know many people my age who are frightened by the concept and go through an existential crisis whenever they contemplate death.
Maximizing longevity is increasing the quality of the time we do have. More time available equals more time you are able to spend doing things you actually enjoy. I feel a great deal of pressure to accomplish certain things given the very little and limited time I have available to me. It's a source of stress that would be alleviated if there were more time available to me.
Another way to look at it would be -- How much more stressful would our lives be if the average lifespan was 40 years instead of 70+?
It’s tempting to say less, since they arguably had “simpler lives.” But it’s also easy to say “more,” since they had a much more present risk of death than we do.
My hunch is that stress is (mostly) relative, and that (outside of trauma) how much one experiences is determined more by ones worldview than ones circumstances.
If you lived longer, would you feel better or just feel the same pressure with different goals?
Accomplishing something is great, but it's not quality time. Quality time is the time spent working on the accomplishment, which doesn't depend on living to see the result.
Anti-aging, on the other hand, has basically no resources spent on it, and would benefit everyone if we could figure it out. It’s definitely worth putting way more effort into.
It’s also not zero sum. We can and should do both.