the tragedy from accidents would increase suddenly while our ability to mitigate them lags

If you mean that humans intuitively measure things on a comparative scale, and thus increasing the value of an outcome that you failed to get can make you feel worse than not having had the chance in the first place -- yes, I agree that it is descriptively true. But the consequentialist in me says that that emotion runs skew to reality. On reflection, I won't choose to discount the value of potential-immortality just because it increases the relative tragedy of accidental death.