From: Shrewsbury UK
It's no accident that WWII is seen as largely European centred. In the 19th and 20th Century, the 'West' was the powerhouse of the world, with a hegemony that extended (almost) globally. The two world wars were when Europe tore itself apart, ultimately losing it's top seat in the world, whilst handing the baton of the West permanently to the US.
The war in Burma and Africa were fights over the west's possessions. But the ETO was a fight in the west's back-garden, and indeed the lounge and kitchen. That's why the war is considered to have started in 1939.
The US could have gone to war against Japan in '37, but if Hitler hadn't attempted to dominate Europe then it would just have been seen as another war, like countless others.
Roosevelt recognised the tipping point of history taking place in Europe, which is why he wanted to get involved, but many at the time in the US had good reason to wonder why so much attention was being given to defeat a nation that, although having declared war (rather pointlessly), had not attacked the US, whereas Japan appeared to be on the verge of doing so.
The US could have lost all it's influence (which is what the PTO was all about, ever since US gunboats sailed into Tokyo harbour with guns blazing in 19th Century) in Pacific Asia, without threatening US completely, since the US was not reliant on it's possessions in SE Asia, and it was still only a growing power, so didn't have much to lose.
Britain and France, on the other hand, were on the verge of being knocked off the world throne, so weak had they become. Thus Stalin, Hitler and Roosevelt took very great interest in a throne that was about to become vacant, at a time when it wasn't clear which nation would get his ass on the seat. In the end Hitler got beat, Stalin beat him but still found himself 'outside' of Europe's heart, and Truman (since Roosevelt didn't quite make it) got the throne, plus the debt of the old Kings (England and France) which yielded much to the new power in the world.
And the Japanese got settled in the end too, in spite of the lower priority, which saved the new power from having to go to war again to take it's lost possessions back.
The fighting was done all over the world, and everything was interdependent, but History is cruel, and while all battles or campaigns influence events locally and in the short term, only a few have a truly long term effect on the passage of history (not always realised at the time), and it's these that future historians remember the most.
One day, when China, India or even Africa (in about 200-500years time) are the ruling powers in the world, and Europe has fallen to the state that other once great civilisations (Greece, Egypt, etc) occupy, THEN, a war of total ferocity in Europe will be shrugged off as just another squabble among degenerate states (which is how we see Somalia and Sudan now) that will barely raise eyebrows in Beijing or wherever the world's biggest stock exchange ends up.