Do you think the OP was just trolling?
Anyway...
Dear OP,
I am not an historian. I do hold a minor college degree in history (1988), which qualifies me to pretend to know the terms Ides of March, Magna Carta, and Casus Belli. That being said, let me pull up my soap box...
Short answer: Our loved ones fought in it. It was Good vs. Evil. The aftermath of the war defines our world.
Long answer:
Let me say that most every following sentence contains at least one oversimplification...
WWII is so close in time to us.... that many of us knew and spoke with our parents, grandparents, uncles, teachers, pastors, doctors, nurses, bosses, co-workers, and neighbors about their experiences in the war. Many of us did not get one hundred percent of our information from textbooks... we received first hand accounts from eye witnesses. My great uncle Gib told me of his work on an aircraft carrier in the Atlantic and the Pacific. Another great uncle, who fought in WWII, was nicknamed Yank by his relatives... everyone called him Yank... in the late 80's, his wife still called him Yank!
And when we did not get the stories from our grandfathers, our fathers told us of their bravery. I don't know how many times my father told me about his uncle Junior... a paratrooper in Operation Market Garden.
And audio and video of the death and destruction, took the war to even those who wanted no part. It was inescapable.
People can suggest root causes and unseen objectives for war, but at least on the surface, if not to the core, WWII was fought over ideology. How will the human race live? As bullies or friends? Promoting euthanasia or goodwill? As superior races or neighbors?
WWII was not fought because Hitler's great grandfather had been Duke of Krakow and Hitler sought to assert his claim. Lebensraum is not the same thing as hereditary title. (Not that I'm big on hereditary title...) Operation Himmler and the Mukden Indicent were shoddy attempts to give a casus belli... for the aggressors to gain lebensraum.
For the most part, I do not believe international war has been waged for ideology. Our -ism versus their -ism. Civil wars? Often. Wars between nations? Not as much. I think most wars are started for anger, greed, pride, glory, lust, jealousy... at least six of the seven deadly sins. Both sides desire to portray themselves as morally right.... and in a war between kings, languages, ethnicities, and religions this is a fairly easy thing to do.
Yes, the European Wars of Religion, the Napoleonic Wars, and most civil wars can be explained in terms of ideology.
WWII was fought on one side by Germans, Italians, and Japanese against the Poles, French, Brits, Russians, Chinese, and Americans.... I cannot imagine a greater oversimplification than that. Of course, I've omitted Canada, Australia, Belgium, Netherlands, Norway, Brazil, Philippines, India, and a hundred others on the allied side. What about Albania? They repulsed Mussolini's attack, but after being conquered, their fascist government joined the Axis. Was Finland in the Axis or merely defending themselves against the Russians? Romania. Bulgaria. Hungary. What about Vichy France? How many of them were killed by the Allies? And didn't the Americans field Japanese units?
There is not an equitable nor easy way to list all of the combatants. Most of the allies had been involved in the Soviet Union against the Reds during 1918-1920. They allied against the Nazis, but they disliked each other at best.
What I'm saying is that WWII could not be easily qualified for King and Country, For God, For the Motherland, by language, by race, by religion, or by hereditary claims.... Each combatant (each nation, each person) had to qualify their involvement. Since none of the old reasons were easily applied or believable, they fought for ideas.
Germany:
Lebensraum.
The superiority of the Aryan race.
These were the ideas of the Nazis. These were their excuses... Since the German peoples were so numerous and needed more space in which to live and since the Slavic/Jewish/Gypsy peoples were inferior, then the Germans (as the banner bearers for the Aryans) could murder them at will.
Japan:
Other nations blocked all access to natural resources.
Superiority of the Japanese race/culture.
These were the Japanese reasons for war. Since the Japanese were racially and culturally superior to all others (they were descended from and blessed by the gods) and since the lesser races would not equitably share their natural resources nor put them to the supreme use of enhancing the Japanese culture, the Japanese were justified in murdering them.
Italy:
Ancient Rome was the greatest civilization.... ever.
This was the Italian reason for war. A lot... I mean a whole lot.... a lot of wishful thinking went into the Italian casus belli.... and their ancestors invented the term. Anyway, because they were the descendants of the Caesars, this meant they could murder Ethiopians and Albanians.
And because of the need to respond to such asinine reasons, at least on the part of the USA, the war became a war of ideology for us. Capitalism vs. Fascism. Republicanism vs. Totalitarianism. Rescue vs. Murder. Good vs. Evil.
And I feel that war is now mostly about ideology....
I also think that WWII holds a place for us, because we were all involved. San Marino, Luxembourg and Denmark did not want to get involved, but they were not given a choice. Goums, Sikhs, Mongolians, Thais, Cypriots, Somalis, Haitians, Samoans, Kenyans, Croatians.... almost every single nation was touched by the war. Few events have had such connections.
And also few events have had such repercussions.... Japanese-American Internment Camps, the Marshall Plan, the Monnet Plan, the Chinese Civil War, Breton Woods, Black Tulip, the Berlin Wall, the Iron Curtain, the Cold War, the Arms Race, the Western Bloc, the Soviet Bloc, the fear of MAD (mutually assured destruction), Reza Pahlavi, Mao, Tito, Nasser, the United Nations, Decolonization (in and of itself, this may be the largest repercussion of WWII... the independence of Africa and all the subsequent wars to the present day), India, Pakistan, West Pakistan, Israel, Lebanon, Syria, Jordan, the European Community, NATO, the Warsaw Pact, the 1948 Arab-Israeli War, the First Indochina War, the Korean War, the Suez Crisis, the U.S. and Soviet space programs, the Vietnam Conflict, the Six Day War, the EU, Japanese apocalyptic art, the remarkable economic recoveries by Japan and West Germany, the 1973 Arab-Israeli War... that is to say that we are still living in it.
(Thiat section looks a bit like Billy Joel's We Didn't Start The Fire.)
Maybe, in a hundred years, historians will be able to definitively state the aftermath.
Just my thoughts...