This is fault of the conservative government, entirely. They still refuse to teach their children about the war atrocities Japan committed (Rape of Nanking, treatment of war prisoners, Unit 731, etc.) or the Holocaust and Abe's government has been leaning on the Emperor and his family to support their desire to re-write the constitution so they can have a standing army again (basically because Japanese Conservatives idolize the Samurai-inspired Imperial Army). It's clear that Abe wants to engage in the same sort of adventurism that China is currently involved in, basically to restore Japan's image as a super power.Japan's typically tone-deaf attitudes toward the politics of WW2, which naturally might be rooted in being on the "wrong side" of that conflict, show through clearly in this series. Furthermore, it only takes a few episodes before the anachronisms (that could be waved away by it being a parallel world) heap up, and the "WW1" settings starts becoming rife with WWII imagery, technology, and metaphors.
As such, a lot of up and coming Japanese authors kind of... don't understand the big deal about Nazi Germany. And it's really not their fault; aside from that period in history, Germany (mostly Prussia) and Japan have always had a very tight-knit, positive relationship and that stuff IS taught in schools. Hell, Japan's Diet is based on the German Bundestag.
This has been an ongoing problem and is sort of why I've stopped enjoying Attack on Titan... the author seems to be going full on fasc and seems to believe this is a good thing.