So if we could strike at the root cause, and heal DNA damage, then we wouldn't have to worry about cancer, and we would be able to turn cell division up and become more youthful. Or alternatively if we could develop better cancer cures, we could turn cell division up and deal with problems as they arise.
Now DNA damage isn't the only thing we would have to fix. For instance some poisons and junk cannot be eliminated by the body and stay with us permanently. We would need to find ways to clean them up.
It is not. It is tuned to pefection. You are _made_ to die, it is builtin, it is a feature. Notice how from 0 to 20 you don't "age", you just get stronger and better. How? Some species are considered young in their 40s.
You consume enough nutrients and energy to constantly fix yourself. You won't. Why? You need to die for evolution to work. Just die already.
A counterargument is that past generations lived too rarely to the point of natural death ("Intrinsic senescence") to experience selective pressure. I feel the burden of proof is in showing this.
An interesting discussion is whether or how an encoded trait that's negatively selected for is different than one that was never factored into the equation.
That's a big if. We've spent millions of year evolving to last long enough to reproduce and care for our young. Beyond that, our bodies break down in all sorts of ways ("aging"), and "curing" all of them seems unlikely. Shortening telomeres, reduced muscle and bone mass, slower metabolism, macular degeneration, worn cartilage, arterial plaque...
The ultimately smart thing to do would be to make our current 80 or so years of life as healthy as possible.