He's actually said a few times now that there was going to be an explanation for why she existed in FF14, in fact he even said it during the event they announced it to begin with. The problem was that people were getting so irrationally angry over her existence that that bit of information kind of got lost.
Still, I don't think ANY explanation will quell the rage her existence has caused, because it's still the real Lightning and not just a Hyur that looks like her.
Still, I don't think ANY explanation will quell the rage her existence has caused, because it's still the real Lightning and not just a Hyur that looks like her.