We tell ourselves things like "life is beautiful only because it ends" so that we can try and accept the inevitable. In reality, there is nothing beautiful about entropy's unraveling of a lifetime of learning, growing, and forming social connections. If it was, we wouldn't have come up with a million fantasies about how we'll totally live forever after we die. There is also nothing "natural" about accepting death if we can help it. A brain that can come up with solutions to carry on life's mission forever is nature's greatest triumph. Otherwise, what is the value of life to begin with? Just a collection of organic matter that assembles into higher order of complexity only to be snuffed out over and over and over until the sun swells up and swallows everything? I think not. We have a chance to break the chains that bound all that came before us, and burst forth and spread across the universe! The Earth has produced a variation of living matter that has the potential not only to outlive the planet of birth, but everything else as well. In my view, that's the ultimate prize. Survival all the way until the heat death of the universe trillions of years into the future. Consequently, I am not interested in any philosophies that define the word "natural" to imply limiting what we can do with our intelligence.
I won't discuss the implications of immortality on the soul or any other mystical mumbo jumbo. Sorry. But I will address two points brought up in the thread.
First, immortality would of course be optional. I doubt many people would want to be stuck living forever, but immortality will give you the choice of how and when to die. We're talking about immortality achieved through knowledge, not the immaterial kind people sometimes bring up. And this immortality is achieved by stopping the aging process after a certain point (say age of 30), along with defeating disease. So no, you would not keep on aging until you resemble a mushed raisin.