The rebuttal to this is life-extension, but I have to say that's not something I'm looking forward to. First, a future with people living dramatically longer is going to be one with fewer kids, at least at equilibrium population levels. Second, it will slow-down social change and innovation. Even if scientific advancements can help people retain their creativity, anyone at 80 is going to be burdened by decades of assumptions. Imagine if the generation that stood behind George Wallace when he said, in his inauguration speech, "segregation now, segregation tomorrow, segregation forever," were still the core of our body politic.

There is no higher social benefit to life extension, at least none that I can see. It's a uniquely individualist/selfish technology.