You don't need to kill off characters to make them interesting-but after 8 years of this ridiculous amount of plot armor and fakeouts people are just out of patience. Doesn't matter how, just get the yes-men off the screen.
Lackluster backstories combined with nonexistent goals gives me hardly any reason to root for any of the scions besides Estinien. After everything characters like him and Ysayle had been through, why should I care about Urianger and how he was bullied for reading books? Top it all off with their barely-present personality traits and overt fanservice "slice of life!" scenes just wears my patience down further.
Remember when Celes attempted suicide and jumped off a cliff into the ocean in what was one of the most beautiful and dramatic scenes in the entire FF series? Or when Garnet cast down her tiara as she ran to embrace Zidane in a genuine display of emotion? The numerous times when Zidane and Steiner went at it with each other? Lightning punching Snow in the face in response to one of his long-winded "hero!" speeches? Even Jack from Stranger of Paradise is more interesting, outright rejecting the stereotypical fantasy nonsense going on around him because he just wants to kill Chaos and probably go out for a smoke.
Half these scenes I mentioned above would be too problematic or traumatic for some fans of this game to handle, it seems. Imagine the reaction twitter would have if we ever saw a character with Zidane's personality re-emerge in the series. Instead we get G'raha Tia and the fanclub go out for hamburgers: the expansion! Can't wait to go get sushi or something with Thancred in 6.1, hopefully the story of Myths of the Realm will make up for the lack of anything interesting going on with the main cast these days. The writers need to ask themselves:
What is this character's main goal?
What is this character's motivation to achieve this goal?
Who does this character get along with and who do they dislike?
If the answers to these questions are nebulous ideals, "supporting my friends," and getting along with just about everyone under the sun who isn't an Ascian or Garlean then respectfully there needs to be some reconsideration in how to handle these characters moving forward. Add in the building blocks that are missing, or let them take an extended vacation.