If this was your takeaway, you can't have been watching it that closely. The British high command is presented significantly less favorably than their German counteparts (sans Ludendorff who, much like his
real life equivalent, was pretty fucked up), there's a whole moment where Diana realizes that neither side is really morally superior, the actual God of zlWar was playing a Brit...
The movie presents the german forces as villians, period. Diana fights on the side of the British/US to defeat Germany. At the very beginning the Germans attack and kill the heroes, Amazons, while the british Spy defends them. We then see how one of the main characters destroyed a german facility in which a crazy scientist tortures innocents and tries to develop a chemical weapon
in the name of the german army. It's not like Ludendorff goes against the will of his superiors here: The Germans want those weapons, they want to use them - Ludendorff just wasn't fast enough for their liking.
We see Diana crossing the No Man's Land while being shot at by the villians, the germans, until the good guys, the British, triumphantly manage to storm their positions and kill them, only to continue killing them in the villiage which they hold hostage. The british forces free the innocent village from the grasp and the evil germans and continue to sing and dance with the villagers.And so on. And so on.
Compare that to a single scene in which a bunch of british generals state it's more important to finish the peace treaty instead of going on a hail mary mission that could jeopardize it, which isn't at all a villanous action nor is it treated as one. And then there is also that one scene were the native American soldiers says that Chris Pine is also kinda bad, I guess.
Then there is that one scene were the german generals want to accept the peace offer, but it's not painting them as some benelovent force. They just lost the war and they are willing to accept it. That doesn't change the fact that, throughout the movie, they are and were painted as the villians of this war.
I talked with a few people in the Foyer after the movie and two of them were actually confused for quite some time because they thought it actually was a WW2 movie, since the germans were simply treated exactly as faceless, evil force of the Nazis in WW2 movies.
I don't want them to go into huge detail about the intricacies of WW1 in a silly superhero popcorn flick, that would be crazy. I just don't want them to take a real war with all its (bloodless) gore and horror and dead civilians and tragedy and then go "Oh fuck, but we need villians, let's just go with the germans!".