Death is by design and is a vital part of evolution. I don't have issues with trying to make our human lives a bit longer (and preserving same quality of life), but achieving biological immortality would open a lot more problems.
But even if it was, why should we limit ourselves to evolution? Evolution did not design us to go to the moon, to split the atom, to have transplantable organs, to fly, to brush our teeth with fluorinated toothpaste, or to use contraceptives — it has only just managed to keep up with us wearing clothes and cooking our meals.
This betrays a deep misunderstanding of the mechanics of evolution. Design is literally not even part of the equation. I suspect you actually know that, but may have let an emotional response confuse your position.
Radical ideas like "let's stop dying" often evoke powerful irrational responses from all sorts of people, but it's very important to stop and consider the source of that response.
For example, I'm envious of those who would live in an age of immortality (if it were to happen), as I don't expect such an outcome for myself, but I don't want to take that away from them if it's a real possibility.
It's very easy to be overconfident where the boundary is between fairy tales and engineering, the boundary between fairy tales and science is even harder, and even domain experts can get that wrong in both directions.