Nature doesn't care about us (or anything), and our genes don't care about us (only about being replicated). But we care about us, and if we don't take charge, nobody will. Reducing our suffering and making our lives better is a noble goal. It's the same as helping someone on the street or caring for a sick friend, except on a much larger scale.
> So? I've had relatives dying, not that big of a deal. They live on in the heritage they leave behind (like their children).
That's fine, you can refuse to take the medicine, then. But those that want it should be able to develop it.
> Very low birth-rates so that some old farts with money can live longer?
So that everybody who wants to can live longer. Once these things exist, there'll be such popular pressure to make them accessible that it won't be a choice, and like all technologies, at first it will be expensive and won't work very well, and later it will be very cheap and work well. Even if not everybody gets it simultaneously, it's still better if it exists than if it doesn't.
> What do you think, those vaccines or those modern HIV treatments are getting to poor countries like those in Africa?
Would things be better if those vaccines didn't exist at all? And yes, they are getting there (ask the Gates Foundation or Larry Brilliant about his work on smallpox), just not as fast as most people would want to. But that's not the fault of the science.