Well, to be honest I already am very good at dealing with death. I've had family members die of old age (some unexpectedly) and friends my own age die. A guy I used to play road hockey with as a teenager dropped dead of a heart defect he never knew he had at the age of 25 a number of years ago. It's a shock when it happens of course, but I've always been very good at dealing with things like that and moving on. While that person may be dead, I'm still alive... and I'm sure the dead person wouldn't want me wasting part of my own life mourning them. Likewise, when I eventually die, I don't want people standing around mourning me. They have their own lives to live and experience.
Mourning is a natural part of life as much as death is. It isn't a waste if it is done in moderation. You treat it as if life should purely be about efficiency, which is mechanical and artificial feeling. Life should be organic in that we experience death and realize that while life is fleeting, it should not be taken for granted. If it's about your personal feelings on death, then make your funeral different, like the Louisiana ones where there's a freaking parade almost. But you can't use mourning as a basic human practice related to death as an argument for why immortality is superior, since that reduces humanity to just living and no sense of change, no loss, no give and take.
To quote the Mythbusters: Failure is always an option. It doesn't matter if you live until the end of time, you're still going to make mistakes. In fact, at some point you'd set the record for most mistakes ever made by a human being.
It shouldn't be about a competition, it should be about seeking knowledge to benefit others and oneself.
And I reject your idea that immortality will make helping each other un-needed. A great deal of joy in life comes from social activities... how much fun would it be to play a game of baseball or poker by yourself? Most things we do require other people, and we are by nature a social species. I see no reason why you'd even think an immoral person would eventually be drawn to the life of a hermit.
If it is an individual immortal, the likelihood of being a hermit increases. But even a group of immortal individuals are not by necessity going to remain social beings forever. Even if there isn't any physical degeneration, we have to consider the psychological aspects of such a prolonged amount of social interaction with no sense of the significance of life in its transience. If I just experience something in perfection forever, I cease to truly appreciate it.
And as I said, familiarity with everything will not ever exist, as new things are being discovered every day at a pace that is impossible for one person to keep up with.
This is a matter of time, though, which still could be comparatively measured, if not on a much larger scale. Eventually the possibilities would dwindle down, even if it took ten thousand or so years.
Sure immortality is unnatural, but then again so is this computer, and the pizza I had for dinner. Unnatural does not mean bad... in fact in many cases it can be a welcome improvement.
Unnatural and artificial are markedly different, however. Unnatural is something going against the natural order of things, such as someone trying to create a disembodied existence. Immortality is similar in that it is almost a necessity that things die. The population control consideration has to be brought up too. We have a cap as to how many people can live on this planet and even if food and drink weren't options, there is always the possibility of peoples' baser natures coming into play.
In a world where knowledge was static, and we never advanced, you are correct, an immortal person would one day learn everything. However, that is not the world we live in. Again, our knowledge as a species is not only growing, but it's continuing to grow at an ever increasing pace. This process will likely never end, and will provide you with new information, new knowledge and new things to do for an eternity. There are 400 Billion Galaxies in the observable universe, and each one contains billions of stars. There is no way we're going to run out of new things to explore and learn about before the universe itself ends
If you have no seeming limitations at all, such as no need for food or water, even sleep perhaps, then immortality would become the worse kind of existence, since you would have no sense of time's limitations, since there would be nothing holding you back. And even if there was, we project a huge amount of time that overrides any of the hindrances of food/water/sleep, so eventually there would be a sense of apathy, in that you have no real motivation, since you can put something off indefinitely.
Assuming there is a remote cutoff point, then immortality is merely delaying the inevitable, since immortality is not necessarily the same as indestructibility. If heaven or some such afterlife is a factor, then that becomes a living hell, does it not? It's one thing to propose a secular immortality, which by its nature would have a limitation of billions of years assuming this solar system outlives its usefulness. And even the universe itself cannot continue forever, so there is a cut off point regardless. But my critique is especially directed towards supernatural immortality, where there is no time frame
