In high school, the causes of WWI were taught to be a huge mess of complicated events that were, "too complicated to get into." I get that war can have a lot of factors, but if that's the case, why isn't WWII taught the same way? We're taught that WWII is just the Hitler thing, but I can't even tell you a single leader of the Central Powers. Why is that and why is it taught that way?
Edit: I get that different schools teach things differently, but overall, WWI is taught as more complex than WWII.
I've written some of my thoughts on why explaining the outbreak of WWI is so complicated in a previous thread here that may be of interest.
I think the conclusion that has to be drawn is ultimately that the outbreak of WWI is, in fact, very complicated. Christopher Clark, who wrote what I think is a very good book on the outbreak of the war that clocks in at something like 600 pages describes it, towards the end of the book, as the the single most complicated event in modern history. It's impossible to judge such things, but if we were making a barroom discussion out of it I think a lot of historians would say he's probably right.
I can't speak to your specific educational experience, but I remember my own (in middle school actually) and we were basically taught the Guns of August version focusing on the MAIN causes of WWI:
The problem with this, while it's suitable in a lot of ways for introducing students to the problems of WWI (you can see it here in a social studies curriculum guide) is that it's basically wrong. Niall Ferguson's The Pity of War, as an example, does a good job of mythbusting many such beliefs about growing nationalism or the importance of revanchism or what have you.
The other issue is that even looking at those issues as the "cause" of WWI, as I try to argue in the thread I linked to at the top, is that they're actually quite detached from the events as they occurred. The MAIN causes did not dictate events in Sarajevo, nor do they sufficiently explain the July Crisis. Likewise, merely explaining what happened on a timeline between June 28th when Franz Ferdinand is shot to the 4th of August when Germany invades Belgium does very little to explain why this war became "The Great War" on a scale that would have been unimaginable even a generation earlier.
For that you need to talk about historical context, the second industrial revolution, the advent of modern banking systems, globalization, the centralized nation state, international diplomacy and the basis of the alliance structures, and so on.
All of this of course is true of WWII as well, but in a sense WWII was not "new" given the experience of WWI. Except insofar as people study the rise of Hitler and the Nazi party in Germany, no one could really be confused about how a European general war on a massive scale could break out in 1939 precisely because Europe had already seen one in 1914. Events also tack more closely to outcomes. How you get from Serbian nationalists shooting the heir of Austria-Hungary eventually resulting in Germany invading Belgium is complicated in a way that Hitler invades Poland, France and Britain declare war on Germany to defend Poland is not.
I'm not sure that sufficiently answers the question, but this and the previous post are some of my own thoughts on the complexity issue and I'd be happy to try to take on followups.