Your argument is a sophism: First of all this is not the design used in Crisis Core or Kingdom Heats (it's more round), also your proportion scheme doesn't work since it's not accurate in size and just scaled to correspond to line, and your exemple of realistic representations are exemples that are precisely made to be creepy.
My argument was not a sophism. I altered the images in no way other than proportional X/Y scaling. I'm not attempting to pull the wool over your eyes, nor do I understand the benefit of doing so.
The examples I pulled from an image search are not altered to conform to the scale. The Pixeloo renderings are indeed creepy and exagerated, but I think your preferred version of Aerith looks weird too. Her eyes are too low on her face and her head is too wide for her proportions. It fits neither the conventional scale nor the manga/anime scale. Given that nobody else in the game exhibits those traits it would look jarring to see one character with different facial proportions.
The character models I used were from Crisis Core, Advent Children, Kingdom Hearts II, and official Square/Enix art.
Here's direct sources for you. Nothing is altered, links to videos included where applicable. Comparing the images directly together the facial structure is not much different between them.
Advent Children
Crisis Core
Kingdom Hearts II
7 Remake
Square/Enix Statue
Kotobukiya Figure
Human proportion scales are among the first things I learned in art classes I've attended. Drastic departures from it will look odd unless the overall presentation accounts for the departure. To remedy this, you'd have to reproportion the character's body and you'd have to change all the characters in the game to match. Once you've altered every character to conform to the new style, they are now part of another style of imagery and no longer fit in with their surroundings. When all the characters are slightly more squat, the environments have to support that style, which they currently do not. Doorways, buildings, steps, railings, chairs, cars, Cloud's bike, etc. Everything must look proportionate to the changes or the whole package will look off. I can guarantee the artists that are working on this game have those things in mind and have put more thought into Aerith's design than either of us.
The game is clearly aiming for realistic proportions, as Final Fantasy has since Final Fantasy VIII (IX being an outlier). Ideally in art a realistically proportioned average height woman will be roughly 7.5x the height of their head (a man is 8x). I did not invent this scale, it has been used for a very long time, long before I was drawing my first stick men 37 years ago.
Examples of the body scale
The head scale is similar. Men and women use different scales here too, and there are variations on the scale but they all follow the same basic principles. The scale accounts for the majority of the earth's population. When expressionless, almost every person on earth's eyes are located directly in the center of their face. The distance from a person's chin to the base of your nose, then to your browline, then to the top of your head are three near identical measurements. Ears are nearly always between your browline and the base of your nose.
Then I understand your point, I don't think there's subjectivity to that and there's absolutely by best judgement a better design, but it's really hard to juge indeed, if you prefer the "new" design which I would say is unfaithful, uncharismatic and overall has proportion and trait design, however I can only say I prefer (not certain if better, but pretty sure) the design in the exemple.
Let's see what Square-Enix does after prospecting.
I don't prefer this design though, I grew up in the early '80s. I prefer how Final Fantasy looked before Final Fantasy VIII came around with realistically proportioned characters. Like you, I would prefer the game to have more charismatic, animated characters like the older titles. Final Fantasy IX got my hopes up but they went right back in X. I would prefer they remade all of Final Fantasy VII in a style closer to Final Fantasy IX. I would like to see a Final Fantasy that looked more like Yoshitaka Amano's artwork to be completely honest.
My argument was that since the game's artists are apparently going for the more realistic proportion approach they've adopted since Final Fantasy VIII and all the characters and environments follow that, changing Aerith will make her look disproportionate to her surroundings. If they are going realistic, I prefer they keep the proportions of characters in that direction. If they had chosen to be faithful to the original game, they wouldn't have gone the more realistic route they did. I think people arguing she should be left alone are correct, despite not really wanting the more realistic art style in Final Fantasy the model they made fits the game better as it is.
I don't expect them to change the design.