Even experiencing loss and finitude is only possible while alive. In a world of immortals you could still have a break-up or have someone you care about move away and lose touch with them. Taking something for granted is not a guarantee of permanence, with or without death on the picture.

We only think of death in regards to life, but there are plenty of things that are never alive. What does happiness and sadness and living means to a rock? It doesn't mean anything because it's not capable of comprehending, much like a skeleton.

Attachment may lead to suffering but survival is ingrained in our nature. We don't just give in if we have a particularly bad illness, nor do we want the others around us to give up so easily. Our civilization has put great efforts so that we don't have to be stuck with the lot that we are handed. Maybe it would be more peaceful to give in, but often would rather fight against tragedy. Life wants to live.

I wonder if it we would even have such lofty thoughts about death if it wasn't for the human propensity to philosophize and ask existential questions.

In a less animalistic sense, I would rather cherish life and fear death, than be impassive to both. Passions add great richness to our lives, even when we struggle because of them. And who knows, every now and then we manage to overcome the tragedies that we could have just given into, maybe one day people's lives will be much longer and happier because of it.