Wilhelm II kind of deserved to get executed. The deeper you look into that guy the worse he gets. Obviously there were bastards all around but that shit was genuinely his fault.
Didn't happen, obviously, because consequences are for peasants.
In WWI, Neither sets of soldiers wanted to be there. Neither wanted to fights, and neither had been conditioned to see the enemy as subhuman.
This led to numerous examples of comaradary. The most famous example being the Christmas football match.
WWII was the first example of industrialised propaganda. The Nazis were conditioned to believe they were truly better, and so capable of doing the horrifying war crimes we now know happen.
WWI, the command was fairly evil on both sides, but the grunts weren't involved.
WWII, 1 sides command was particularly evil, and the grunts were convinced to agree with them.
WWI - yes, not necessarily specifically bcs of Nazis (one solder is just a human, exactly like the enemy solder), but because WWI was much more contained in fixed fronts, soldiers vs soldiers. Back then they still avoided civilians (but then tech advanced).