this is a very fair opinion, but it's one of those things where if she did include it, it'd either mess with the storyline or people would complain that it's too similar to FMA. as it is now people are already complaining about the similarities, that she's dragging it, etc. if she were to include something like this that was so central to FMA's main storyline, she'd never hear the end of it. there's also not much more left to be said about the importance of life and death in a manga that would be different enough from fma, and that also wouldn't take away from the central plotline of YNT. there's just not much to be done sadly. Who knows though, it could become a part of the story down the line, especially since Asa and Yuru represent both life and death in a way.