For people who keep posting this kind of thing, we actually know quite a bit about stella added up from the trailers and the information given out about her over the years, even if we don't know about how the story went exactly with her in it.
So for changing her in the story, it actually represents a fairly big shift in the direction of the game's overally design.
The entire point of the name "Versus" was because Stella and Noctis were supposed to be two complete opposite forces, like their respective Kingdoms, and they were supposed to likely duel over love and battle.
It was essentially a romeo and juliet type story where they meet at a party, she keeps her identity a secret and ended up being an agent for the other side even though she and Noctis shared the exact same situations of near death experiences, having the same power, and responsibilities to their Kingdom.
In changing her, they are essentially taking out that Versus element of her character, and thereby changing the entire point of the game. They are no longer going to be forced to fight each other, she will be relegated to looking pretty only, and probably not do much if the recent trailers indicate anything.
Its a shame for female representation and the actual interesting dynamics of not just fighting enemies.
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