We can adapt without dying, thank you very much. In fact, traditional death-based evolution is probably hindering our adaptation more than it helps, since it takes a few hundred thousand years to do what we can now accomplish in just a few decades.

We've already thrown out evolution, which isn't a huge deal because our environment is changing far too quickly for it to be helpful.

But even if none of that were the case, arguments that death is a positive and should be kept around have a huge burden to meet. When your argument is "we should murder everyone who will ever exist because X," then the value X had better be pretty fucking huge.

Not to get political but have you seen the makeup of the US Congress? The world is ruled by octogenarians that never seem to die.

Not really an argument against curing aging, but rather an argument for age limits or age-based representation.