Her death wasn’t entirely about her, and it wasn’t resolved in Season 1, so naturally fans demanded justice for her.
The rally cry of “Justice for Barb!” rose up after Stranger Things Season 1 did not deliver closure for her death.
Bob’s death may have been a tragedy, but as Sean Astin says, he got a hero’s death.
The poor girl was brutally killed after being dragged to the Upside Down, and her death was mostly important to the plot because it got Nancy involved in the mystery.