I'll use my favorite game as an example. Tidus being revealed as a dream.

If we accept the premise that dreams can exist in real life. Can interact with us while we're awake or exist isolated from the rest of the world, then what does this mean for existence? How does it redefine what it means to exist? How does it shape the in-game world of Spira to accept that Tidus can even exist. Did the game ever explore these points or were they completely wasted, their potential never being realized. How much better would FFX's story as a whole be if it explored them?