Yeah I would think removing stress and trauma would fundamentally change the game into something else, but you could still reskin them to change the tone. For example stress could be your mana, and traumas could be your soul ascending, or something like that in a heroic fantasy setting; the mechanics are still the same but it doesn't have the same dark vibe.

Ya several of the Forged in the Dark games change the way these mechanics work. They're great fun still.