Do we really need to "come to terms" with death in order to be psychologically healthy? Many would assume that the answer to this question is "yes", but where does that leave the rational life-extensionist?
Some of us today might very well reach some degree of escape velocity, through a combination of healthy living, luck, and simply being in the right place at the right time -- but no one person can afford any degree of complacency. And while the laboratory work and technological development continues, those directly or indirectly involved with such efforts will continue to struggle with developing what we feel is the most rational outlook with regard to the future, and our prospects of living to see more of it than a traditional human life expectancy would allow.
Considering that we don't have real anti-aging medicine yet, and that human bodies are extremely vulnerable to all sorts of random destructive phenomena that could hit at any time, and that the planet itself isn't likely to be a habitable home forever (and we've yet to establish a viable means of escape in the event that Earth does become a fatally hostile environment), a belief that one will somehow manage to escape all possible threats to personal existence for as long as time exists can't possibly be based on much of anything in the way of real supportive data. However, I don't think most life-extensionists see things that way.
Certainty about the distant future is not something any of us can possibly have -- there are too many things that could happen, too much data that could come to light just when we think we might have everything "important" figured out.
This is actually part of the reason why I don't think that life-extensionists should concern ourselves with making sure we come to an absolute acceptance that yes, we are definitely going to die, particularly of age-related causes.
I'm not saying we should all assume we won't die -- that would be just as bad, and less supported by the presently-obtained historical data to boot. I'm saying that making absolute assumptions about the distant future is irrational, and does not add value to any conception of reality, except in the sense of lending someone personal comfort (and remember that it is just as possible for a person to be comforted by the idea of eventual death as by the idea of immortality -- pessimism is a great refuge for those who want to be right a majority of the time without having to personally lift a finger to influence the outcome of events).
What I do think life-extensionists would do well to accept, and come to terms with (and I'd wager most of us already have), is the fact that each of us is vulnerable. With regard to psychological well-being, I think that developing a sense of perspective regarding one's own vulnerability and fragility (particularly with regard to the present human form) can enable people to face reality with minimal distortion -- which, ostensibly, is the same goal that the death-acceptance advocates have in mind.
Except for the fact that we don't make an exception for aging, we life-extension supporters aren't really much different from anyone else in our desire to live.
Try as I might, I just can't see how death due to "old age" is somehow more palatable than death due to a brain tumor or drowning or getting hit by a car -- and yet you'll hear plenty of people waxing eloquent with metaphors about blooming and dying flowers or melting snowflakes or the turning of leaves in reference to aging into death.
Personally, I'm no more a rose or a snowflake than I am an E. Coli bacterium or a blowfish -- poetry is one thing, but it most certainly should not be invoked in the context of trying to convince people that while it's a good thing to wear their seatbelts, it would be a bad thing to undergo treatments that could (for instance) clean up accumulated damage due to old age, or support the development of such treatments.
There's a difference between working to make healthy life extension a reality and "dreaming of immortality". And there is definitely a difference between mythical ideas of immortality and the kinds of lives people are likely to be able to lead in an era of life-extending treatments.
Life extension technology can (and probably will) allow a lot of people more time to live, but it's doubtful that it will ever offer anyone the kind of certainty with regard to continued existence that mythical immortality does. Vigilance and maintenance (it will be interesting to see what is necessary to keep a four-hundred-year old alive!) will probably always be necessary, and regardless of what technology is developed, none of us really knows for sure how long we'll be able to take in data, form memories, and interact with other minds.
No matter how long we live, there's always a chance that we might not live to see another day. But at the same time, the longer we live, the closer we move toward an era when people might be able to access treatments enabling them to live a lot longer than they might otherwise have. The chance that we will live to see another day is always there, as well. And this can be acknowledged without any kind of faith, without any sense of certainty, and without the need to think of onesself as invulnerable or indestructible.
Reality may not be there to cater to your every whim, but it's not out to get you, either.