A story is defined by what happens in it and by character development, Without these things you cannot hope to get attached to any of the characters or the story or care about anything that goes on.
And this, is precisely the criticism XII often gets. No one cares about Ashe or vaan or Solidor or this empire or the people or anything at all. They could be Tom, Dick and Harry. No one can feel the threat of this empire, although that threat is eluded to. No one can feel anything and thus the story is like someone giving you a lump of clay and telling you a great work of art lies somewhere in it if you can arrange it properly.
Without attachment to characters, you will not care about them, and there is no emotion. Without these things you cannot sympathise with their plight/struggle or adventure, and without that, the story is like a cheap piece of cardboard.
For a human, emotional attachment to characters via character depth and development is paramount to a story. The story is more than just a set of rules or quotes or summaries. It is the emotion. If Aerith hadn't have had any character development in VII, when it came to her death, the vast majority of people would not have had any feeling one way or another.
The fact that it is cited often as a pivotal moment in gaming history is precisely because it succeeded in evoking emotion and it could only do that because the vast majority of people cared.
Tetsuya Nomura "Death should be something sudden and unexpected, and Aerith's death seemed more natural and realistic", and "When I reflect on Final Fantasy VII, the fact that fans were so offended by her sudden death probably means that we were successful with her character. If fans had simply accepted her death, that would have meant she wasn't an effective character."
Substitute Aerith for Ashe, and no one would have given 2 hoots. That isn't because the plot point would have failed, but because the actual development had failed.