You DO understand that this first appearance is just her Prologue, right? She's going to be with the Justice League in the modern age, kicking off the Age of Heroes right alongside the other guys. Her next movie will be set in the modern world too. She'll make her mark there. What she did in WWI was never meant to be the game-changer.
And the director of her first solo movie may very well get to direct the next Justice League movie.
You think she'll pass on the chance to make Diana look awesome in that movie, too? I think not.