Her narration voice was equally shitty. If it had been normal, it would have been a far more subtle hint to to her "darker" nature. They could have just done that instead of trying to hammer home in every single scene, in such a ridiculously heavy handed manner, that this girl runs and hides from her problems. FFS.
Instead they went over the top with
everything.
Her character concept is good enough
That's the problem, though. Vanille is the character with the big sobstory that never translates on screen. I don't give a shit about her history if the effect and how its shaped her as a character never makes it on screen. Or if it's done so badly I want to kill myself every time she speaks. You can fill wikipedia pages with mere
information but it will never be a subtitute for characterization. FF13 writers seem to think they're synonymous.