Having grown up in Germany I have firsthand experience how Humboldt's ideals fall short. I don't think I fully agree your explanation.
a) Teachers themselves went through this system, so if it's so great, it should produce plenty of great teachers
b) Now we are blaming the kids for the failure of the system?
c) Yes, absolutely, but is the bureaucracy really inevitable, or is it even contradictory to the original idea?
Anyhow, Humboldt's humanism was ideology from the start. It was a way to change as little as possible from christian values. Instead of God making humans all great now it is the great human mind and civilization.
By now, most of German academia is a bubble for humanistic fundamentalists, that have long lost their connection to reality.
After WWI, the "Great War", everyone thought it was the final war, and would never be repeated. (So no profound changes in the educational system were applied).
After WWII, and observing how it could occur despite the recent occurrence of WWI, it was decided to put extra focus on the horrors of war in Western Europe.
Both on allied as well as axis side, sure, but especially on axis educational systems.
Having grown up in Belgium, I can confirm that the never-ending stream of unprompted details of the horrors of WWI and WWII were not exactly "fun" part of education, but hey at least we haven't been lobbing chemicals at each other for the last ~80 years, so at least it seems to work, here, locally in Western Europe, despite all the side-effects of such an education.
That said, I don't feel confident that any insights that may truly improve education in Western Europe (without losing the pacifying -as in peace generating- benefits somehow) would apply well to educational systems elsewhere, because a large fraction of negative side effects in Western European education stem precisely from the educational pivot after WWII.
What’s so terrible about the WW1 (industrial warfare) and WW2 (industrial extermination) curricula taught in Europe? I don’t think they’re designed to be fun. Quite the opposite.