Him being a Resonant is the result of the human experimentations performed in Stormblood—it’s the artificial Echo that Garlean scientists extracted from experimentation on various individuals—including Krile—and gave both him and Fordola that allowed them to manipulate and perceive aether.
Him coming back again would make him just like Y’shtola—who has “died” at least once every expansion to the point that should she actually die in the future, her death would be emotionally meaningless and have no impact. It’s been a fakeout each and every time.
That’s…not an opinion. It’s simple fact. If your story is undermining the development of the characters within it, then it’s poorly written. There is no “opinion” about that.