Death is not necessary to give life meaning.
Grab a piece of printer paper. It's blank; nothing there. Grab a pencil; add some contrast. Now you're onto something.
Then again, you could have a completely different opinion on the matter. I wish you would have explained it :)
Do you really think this is true, or did you write it because it sounds good?
Life is about self-awareness, not about death. Would your life really change if you couldn't die? Mine wouldn't... although I would probably jump out of my window to get downstairs instead of waiting for the elevator. Death is an implementation bug, not a defining characteristic of life.
Pain is not necessary to understand pleasure. I can enjoy things without thinking about pain to counter it. (Again, pain is just an implementation bug. You can break your body if you are not careful, and pain is your body's way of getting your brain to stop breaking it.)
Finally, I don't look to others to define myself. Other people are nice to have around, but not for the reasons you list.
I don't want to be cynical, but I think your world view is misguided.
How, pray-tell, do you know how your life would change if we couldn't die? It's not something you'll ever be able to experience. Hell, as humans we can't even comprehend infinity. That being said, I'd argue that "life" would change a lot if it were no longer actually "a life." Would you plan to jump out of that window to get downstairs to go to work or whatever for the rest of eternity? How many centuries could you live until it just became... meaningless?
Of course pain is simply "your body's way of getting your brain to stop breaking it" (or something similarly boring, at least). I'm not arguing that there's some deep philosophical reason that pain exists. I'm simply arguing that if you had never experienced pain (physical, emotional, or otherwise) you wouldn't know real pleasure either because you couldn't define it. Logically, you'd have to be happy all the time if you could not experience sadness, but you wouldn't know what happiness was because you never experienced anything else. I suppose you could be truly neutral, but that's the same thing as feeling nothing which, consequently, is what happiness would feel like if it's all you could experience. I'm not saying you need to consciously remember a time you got punched in the face in order to enjoy sex or something asinine like that.
Finally, it's not about looking to others to define you. It's simply about realizing that your "being" or whatever you wish to call it is based entirely on context and circumstance. For instance, if I hadn't read your comment, you wouldn't exist to me. We've never spoken before, I don't know you, etc. Luckily for your psyche, you have friends and family and lots of other people/things to define your existence. If you didn't, well, the fact that you are physically here wouldn't really matter much at the end of the day. Of course you wouldn't just disappear off the face of the earth, but for all intents and purposes you wouldn't exist.
But I don't think it follows that all types of happiness and pleasure would cease to be. Some things might be inherently pleasurable, or rather are pleasurable just because of the qualia (http://plato.stanford.edu/entries/qualia/) of such experiences, and not because of a reference to a prior pain. Orgasms. The taste of a delicious meal. Etc, etc.
Lastly, the absence of pain and death wouldn't necessarily mean that all our goals would be attained - there could still be room for struggle and therefore satisfaction. For example, I don't doubt that if someone with a lot of intellectual curiosity like Aristotle or Isaac Newton or Einstein were immortal and still alive today, they would still be able to find plenty of interesting challenges and probably wouldn't be bored of life yet. For the curious among us, as long as there is the unknown there will always be challenge and there will always be something interesting to do...and in the end, who knows if the unknown is even really finite?
Some things might be inherently pleasurable, or rather are pleasurable just because of the qualia
I completely agree! However (and perhaps I misrepresented my own view here by making things too simplified and black/white for the sake of comprehension) you still have contrast. For instance, an orgasm would likely always be more pleasurable than eating a piece of toast, regardless of whether or not you could experience any sort of displeasure. My argument was more of, "If an orgasm is 10/10 on the pleasure scale and everything felt like an orgasm, it's the same as being 0/0 because there is no longer a scale." Of course the counter-argument here (not much of an argument really) is "Everything would just feel awesome!" Unfortunately, that assumption is made from within the context of a life that does have a scale, so it's meaningless.
Since I can't rightly say that the unknown is finite as I have no idea, I won't argue that eventually Einstein would become so bored that he wished to die. However, I stick by my opinion that if life where eternal it would most certainly redefine the idea of life as we know it and would likely ultimately dilute the experience. To visit the orgasm analogy again, I think life is sort of like one -- a very brief period of heightened pleasure, awareness, etc. If you remove the brevity from it, you eventually remove the pleasure.
I think most people would agree that life is about the moments. The orgasms, the successful companies, the broken hearts. We define our lives based on these moments, we don't define them based on the dull in-between; eating breakfast, taking out the garbage, brushing our teeth. Many of us, I think, strive to fill our lives with as many positive moments as we can mostly because (consciously or otherwise) we realize that we have only so many moments to make before there's simply no time life to make them. If you could live forever, would you honestly work so hard all the days of your long life to make those moments? Or would the lack of urgency dilute your desire for that? Even cause you to eventually lose that desire entirely?
Hell, I don't know. I'm just of the opinion that it would.
However, this leaves us with the problem that not only would there be no change in the intensity of pleasure to actually signify the difference between normal and orgasms (just for example), but absolute pleasure, being the one and only feeling, would become outrageously normal.
Which leads back to life without death. The majority of people (every single person I've ever met) have serious issues with the concept of death. Maybe they're not afraid of it, but we have created entire religions simply because not one of us can imagine being non-existant, and so we created the afterlife. However, the fact that we are is defined by the fact that there are many who aren't. The problem with this idea is not a single one of us can make a conclusion based on our behavior is there was no death, for it is impossible for us (or at least for me) to comprehend a world in which there actually is no end of life. The example given about these philosophers is true, I doubt the would be bored, however the hundreds/thousands/however many years they would have been alive is no where near infinity. Without even a concept of death, life is no longer life, it simply IS. End of story. Our goals may very well be attained, but the fact that they would even be considered goals with no pleasure at attaining them and no pain at leaving them be is a bit of a mystery to me.
That's an unfalsifiable statement, I'm afraid.