Firstly, Infidel753 digs into views on what is and is not "natural":
Most people who think it would be "unnatural" to cure aging so that people can live for centuries probably do not think brushing their teeth is "unnatural", but fundamentally it's the same thing. In both cases, one is using tools created by human intelligence to prevent damage which would otherwise slowly degrade one's health. Since we understand what causes tooth decay, it's perfectly natural for us as intelligent creatures to make and use tools to avoid it. The aging process is far more complex, as are the tools we will need to develop to stop it, but the principle is the same.
What really bothers the hand-wringers, I think, is the radical nature of the transformation which is coming.
Meanwhile, over at the Speculist, you'll find an essay that requires a little more care from the reader when thinking about the meaning of "we," individual responsibilty, and the nature of government and collectivism. This much is clear and true, however:
Eliminate aging and we do away with the pain and devastation that it causes directly, as well as the pain and devastation that it enables via accompanying diseases such as cancer, diabetes, and heart disease. Eliminate aging and we do away with that long treacherous death march of people lining up for their last six months of life and all the expensive medical care that goes with it.
Everything that follows is muddied by our present socialism. The rules made and vast sums of money moved around (and wasted) by government employees distort all businesses, all decisions, all processes in medicine. Once you step into the swamp and start debating which clump of mud should be over here versus over there, then every argument you make has the largely ignored cost of government waste and government regulation attatched to it. Whatever relative good might emerge from your proposals - and even relative good is very hard for governments to achieve, given the incentives of those involved - is inevitably far outweighed by the costs imposed by the very existence of government.
To put it another way, the FDA and the terrible ruin it has made of medicine is a natural outgrowth of a government large enough to fund a diverse research organization like the NIH. So the FDA will latch itself onto any new significant government-funded research venture and make it prohibitively expensive to apply the results, stifling any nascent and inventive culture of for-profit development.
ithin the next five years, it's quite possible that physicians will come into routine possession of a remarkable set of tools - a brand new way of dealing with the frailty and disabilities of aging. The tool kit is autologous stem cells derived from the patients themselves, amplified in culture, and infused back into the patient according to a precise protocol. It would be such a leap from today's medical diagnostics and treatments; it could only be called revolutionary.
The purpose of employing autologous cells is to prevent rejection of histo-incompatible cells by the patient's immune system. But it's also possible that these new therapies could slip from our grasp, at least in the US. If we're not careful, these therapies could become the exclusive domain of the pharmaceutical industry, as regulated by the Federal Food and Drug Administration (FDA). This could push the availability of this tool kit 15 to 20 years into the future. The opportunity-cost in terms of morbidity and mortality could be catastrophic.
Big enough to give you what you want is big enough to take away everything you have - except that governments don't do so well at giving you what you want in the first place. Typically the end result of a "successful" campaign by the public is the worst of all worlds, where whatever resources are made available are siphoned off for short-term gain by connected elites, and the cost of providing those resources falls squarely on everyone else. A call for vast funding is in essence a call for vast corruption and waste, followed by oppressive new regulations that slow or halt private initiatives.
This is the way the world works, sadly. If your future is entwined with the development of a potentially transformative medicine technology, your best bet is to commercialize clinical applications outside Europe and the US. Only there are you going to find regions that allow you the freedom to move more rapidly and efficiently towards therapies.