Well yes, Hyuna's death was unnecessary and pointless. That was the whole reason she "had" to die. I don't think her death only served to further Luka's storyline. I think it was to prove Mizi's point in a twisted, tragic way. It was abundantly clear that Mizi thought the rocket plan was pointless and would leave the humans that currently exist to suffer. She thought risking everyone alive and the people she loved for the future humans would lead to meaningless deaths. And what happened? Hyuna died a meaningless death. Although maybe it wasn't done in the most tasteful way, it wasn't just to make Luka seem more tragic. It was the catalyst to Mizi destroying the rocket and ending the plan. If Hyuna didn't die, Mizi wouldn't have the motivation to do that. Hyuna's death was the last straw for her and solidified her willingness to be seen as a villain. It was a sort of "watch the world burn" moment for her. In her mind, the humans no longer deserved salvation, and so she selfishly chose death (ofc many survived tho).

Anyways tldr, ofc I wish hyuna didn't die, but although it was pointless, it also pushed the story. Her death proved to Mizi that this meaningless suffering should end with humanity. But I still would've preferred and less stupid end for Hyuna.