Seems to me like you are denying the fact that a lot of people didnt like jason. Also what is this rubbish about not making a character a sacrificial lamb. if you need to kill a character to tell a story and you believe the story to be worth it, do so.
To this day Jasons death has been a defining moment for Batman, it may not have been handled in the best way possible, but it definitely wasnt poorly done.
Support characters die all the time in fiction, even protagonists that dont resonate with the audience anymore get killed off. Sometimes it has nothing to do with them, maybe the author just wants to go in another direction and replace the lead. This also happens, its all storytelling. And other than well written stories i have no demands for said characters.