As I mentioned the other day, there are more economic benefits to enhanced human longevity than just the obvious ones. Some of these benefits emerge from systematic changes in the interactions and relationships that make up society: the willingness to consider longer time horizons changes the way in which people value all sorts of things, both in the present and for the future. If fifty years from now is someone else's problem in your eyes, you are unlikely to be a good steward of fifty-year bonds - but if you are going to be alive, vocal and very much in the picture five decades from now, then the way in which you look at these things becomes completely different. You can substitute forests, farmland, houses, familial relations, companies, or a range of other entities for the fifty-year bonds there: we humans instinctively put a value on everything, and there's nothing wrong with that. The more that people value their relationships, possessions, future earnings, and a hundred other line items, the more willing they are to invest in maintaining these tangible and intangible entities.
This incentive to invest and improve is important, because short-termism is the road to ruin in all things economic - and everything that we do is in the general sense an economic decision. All wealth and civilization is built upon the move away from short-termism, to depart from the practice of strip-mining the present because you believe you are unlikely to benefit from the future. As the expectancy of human life increased over the past few centuries, so the time horizons of our ancestors broadened, and they became more likely to take actions that increased wealth: planning for the long term, investing in technology and research, trading rather than war, and building rather than tearing down.
A longer and healthier life is a good thing for individuals, but it is also positive for the whole society. This speech will give a quick description of positive political, economical and sociological aspects of a world with a largely delayed senescence: lower health costs, lower level of violence, higher level of happiness...
As a species, we are of course very much still mad, illogical barbarians by any absolute measure. But we are less so than now than in past generations - less violent at least, and more compassionate, although still just as deluded when it comes to a great many other topics, such as belief in the existence of dubiously benevolent sky gods. A great deal of that progress can be attributed to the changing incentives and values brought by increased longevity - and then the compound interest of small gains, amassed year after year.