The Germans had much better technology and access to raw materials, while the Japenese had much better manpower. Both were incredibly skilled, determined, and had the cahones to do what they did. I don't think - no, I know - it's not as easy as you are making it out to be. Keep in mind that Germany had just lost an entire generation of men, and had their lands decimated, not 20 years before. Their ascension so quickly from ruins, based almost purely on shame and propelled by a booming mineral trade, is to this day an unprecedented phenomonen.
As someone who studied history (particularly War and Society) for one of my minors, I wonder how long the two countries' amicable relationship would have lasted, had the war continued on both fronts for an extended period. Had Germany actually conquered Russia, I would not have been surprised to see the Japanese turn their attention to the Western Theatre and try to fight them off.
And Dex is right, the nuke was as political a weapon as it was a wartime weapon; it meant as a signal to try and prevent future power struggles like this from occurring. Funny enough, after WW2, the US has really been the only true superpower, so it must have been effective.
You definitely need to read up, there are some excellent books out there detailing the leadups to the Second World War and the true effects it had on Western Europe. The best place to start would be finding some books about the Treaty of Versailles and its ramifications: many of these books put its consequences into context of the second stage of Germany's wars. PM if you are interested; I wrote (a very long and boring) paper a couple of years ago arguing for and against Versailles' equitible treatment to the Germans, and its resulting effects. It also shows just how crushed the Germans were after the Great War, first by the war itself, then by Versailles.