Your points are well taken.
Loss is part of life, though.
Loss is a part of our life as it is, without immortality, but with immortality, loss is not so much a major issue.
You can't argue that because there is something undesirable in something that we should do away with it entirely.
To me, labeling something as undesirable is the same as labeling it "something to do away with entirely." Cancer is undesirable, and I would like to do away with it entirely. Immortality would accomplish that along with all other such diseases.
Just because we generate something in our minds as something desired does not mean we should follow it either. Desires are born of ignorance, of greed, aversion. They aren't always negative, but they aren't automatically good because they exist.
This is very true. But desires can be born of knowledge and love just as easily. The desire is not good because it exists, and each desire should be weighed individually.
You're asking for utopia, which is in Greek, a place that literally is nowhere. Paradise and the like are just an escapist fantasy, trying to get away from the harsh reality we exist in. Just because life is hard is not a reason to create some fiction to ease the suffering.
We are not talking about a fiction. We are talking about immortality, and why it is desirable and reasonably so. Utopia, for me, would be a place in which there was no disappointment, everybody would love everybody, and the world would be in perfect harmony, but I do not think immortality would bring that. Immortality would only give us more time to work toward a utopia, while it would still likely be unobtainable.
Time is how we gauge things, yes, especially death, in that with enough time, everything passes away to nothing. Ideas, material things, no matter the size or durability
This is the way of this world to some degree. It can be argued that ideas do not fade with time and merely change and pass from one to another. We would have to know the end of all before we could say that for sure. However, we are not talking about this world or this life we know. We are creating a new life in which immortality exists, and in our new, immortal life it is reasonable to assume that ideas would never have to pass away because the people having the ideas would never pass away.
I wouldn't appreciate my life if I could never die. One could become like the Kurgan in Highlander and keep putting yourself in near death situations just for the thrill of it, endangering others in the process because of your selfish desire driven by insanity and instability.
This is spoken as if you still have at least one foot grounded in mortal life. In an immortal existence, there are no near death situations, and you cannot endanger others. Also, there is no reason to assume that insanity and instability would be any more prevalent than they are now.
So are we talking about immortality existing and why it is desirable, or are we talking about why it is desirable to think immortality exists when it really does not? Those are two very different discussions.