Shakespeare's sonnets are artfully composed, and I'd say we've done a decent job of keeping them around and finding uses for them.
I agree that few people imagining they can have eternal life think that they will suffer. But that's exactly the problem. They haven't thought it through. They don't yet understand what life is. Which is why they are so woefully unprepared to handle the parts that don't match their fictions.
The bit about Shakespeare's sonnets I take to be a counterargument to "all composite things decay". That we have managed to keep 100k of text around for less than half a millennium seems like poor evidence that immortality will soon be ours. People die. Species die. Planets and suns die.
It's a long way to go, or at least a very long shot, but a long life is possible in principle. Things decay, but they can be fixed or replaced (even the brain: current physics says that copy-paste transportation actually works —in principle). We just don't know how to do that yet. Now, about my personal immortality, I see little hope short of Friendly AI or cryonics, and even those are a long shot.
I also agree with you that the various theoretically possible techno-miracles likely won't mean much for us than a modestly longer old age. So I think everybody should really come to grips with what dying means. E.g., by filling out a living will and discussing end-of-life issues with family. If it turns out that preparation is wasted, I don't think anybody will complain too much.