Everyone who advocates for far longer and far healthier human lives, a goal to be achieved through progress in medicine, sooner or later runs into the "death is necessary to give life meaning" objection. It sounds deep, but turns out to be complete nonsense once you start to break it down into its component parts for examination. The meaning of your life is what you decide it to be, and that is determined while living, while being alive to think, plan, and achieve. Living is what is necessary to give a life meaning for the person who lives it, and it isn't as though other opinions really count in this matter. This strangely nonsensical argument for death is really just another facet of the naturalistic fallacy coupled with the lazy conservatism inherent in human nature. It is painting what happens to be the state of the world now as the best of all possibilities, because it is easier to do that than to set forth to change it. There is no state of the world so terrible that you would not find the majority talking themselves into accepting it as the status quo.
It is not uncommon for people to accept, rather uncritically, the stale cliché according to which life gets its meaning from death, and without the latter, it would not have meaning. If rejuvenation can stave off death and extend lives indefinitely, will these extended lives be utterly meaningless? No. Time and time again have I said this before, but I still fear that this misconception may be one of the worst enemies of rejuvenation; consequently, I spend much time thinking about its roots and how to debunk it. Whether life gets its meaning from death or not, people who think it does implicitly admit that life has no meaning per se. In a general sense, this is correct. Meaning is not an intrinsic property of anything. To paraphrase a common adage, meaning lies in the head of the beholder, and that's where you should expect to find the meaning - if any - of anything, life included. In other words, it is up to you to find meaning in your life, and you should neither expect it to have meaning by default, nor let others decide for you what the meaning of your life is.
It is obvious why a strong wish to live exists: if I fear death and try to avoid it by all possible means, I stand a better chance to live long enough to reproduce than somebody who isn't so afraid. Therefore, evolution has penalised creatures who did not have a strong survival instinct, and rewarded those who did. This is why we hold our lives so dear. Human intelligence made us extremely fit for survival; our curiosity and drive to answer questions that we ourselves ask are among the things that make us unique on this planet. Eventually, they made us wonder why we die. Evolution has made us fear death and wish to live indefinitely, but at the same time, it has not given us the means to fulfill that wish.
The first and most evident sign of our attempts to address this problem are religions. Yes, we fear death and don't want it, but we don't really die, only the body does, or so is the claim. Some of us have resorted to accepting it, which seems to boil down to convincing yourself there's nothing to fear in death and you're okay with it. The final way to circumvent the death paradox is the fabled 'meaning of life'. What better way can there be to rationalise death and escape our mortal fear of it than making it what gives life itself its meaning? Far from being something we should fear or avoid, death becomes thus essential, for without it, life would have no point.
What does it even mean, to give meaning to life? Most would probably agree that filling your life with activities, people, and things you love and enjoy is a valid candidate for the meaning of life; so is helping others, or doing something for the common good; something that we feel is appreciated by others, and are thus gratified by. Giving meaning to life might mean doing some of these things, and clearly, none of these potential meanings is given to life by death. However, these are viable options but aren't the answer, because there is no single answer. You decide what is the meaning of your life; not old legends, not old myths, not clichés, not other people; you do. Thus, the only way death could be the meaning of your life would be if you decided so, which I hope you won't do. Ultimately, there's nothing especially wise in accepting death. The natural length of our lifespans is the result of a meaningless, purposeless process that happened for no other reason than the fact it could.