A great movie needs great supporting characters. It's one of the unwritten laws of Hollywood and you can look at any of the most successful movies of all time to see it's true. Seeing those characters face death is often a crucial part of the story, building the tension and stakes to an unbearable level before the inevitable happens.
Titanic became a phenomenon and the highest grossing movie of its time because James Cameron made sure you cared about every passenger as they headed towards their icy fate. Avengers Endgame succeeded in part because of its cold open with the Barton family. Seeing, or rather NOT seeing them vanish was a stab to the heart of almost every one who saw the movie, especially little Nathaniel Pietro who was just a baby in Age of Ultron.
Sometimes it's clear early on that someone is going to be meeting their fate during the film, normally they are the annoying ones. Whether it's the naive rookie who keeps screwing up, the bitchy cheerleader or a kid who is just exasperating, there is nothing more satisfying than seeing them finally killed off.
Except sometimes, that never happens... they might get someone else killed instead, or the story or director just allows them to live, leaving the viewer shaking their head.