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

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.