True. But in BvS she said she turned her back on Mankind a century ago (thus roughly after WWI) so I expected the reason to be shown in the film. Overall, Wonder Woman still does a great job showing that in WWI there wasn't a "Good" and a "Bad" side but simply people. I wish it had done more in that vein, but it's a superhero film, so it's natural that it doesn't delve too deep in it.