The WWII-thingie did seem random... I had the feeling that they had been trying to figure out which time setting could be used without contradicting the other films while having the audience have a particular relation to this specific time. I mean, WWII is still a touchy subject, makes up for a 'good film set up' and provides enough drama and action to start a film with. Plus, so far, we have experienced Wolverine in a lot of different settings, and WWII seemed to be the easiest choice to continue/start with.
It appeared to be more of an arbitrary decision though - as I am not too familiar with the comic books and have seen the other films only once or twice I am part of the 'average-knowledge-audience'- so it made me wonder what on earth Wolverine was doing in Japan during WWII.
For me personally, this had the consequence that the character Wolverine seemed even more impalpable, distant, mysterious. I have never actually felt anything for the character, as in 'Do I like him now? - Do I hate him? - Sympathy? Maybe yes, maybe no...I don't know.'
The WW2 thinggie is not exactly random when it comes to Logan.In the comics, it was stated that he was at one point in the RCAF ( Royal Canadian Airforce).
He fought in WW2, and my knowledge in that subject is more than rusty, but the RCAF were in Asia during WW2.Their 6th division were trained to take part in 'operation downfall' which was the codename for the allied plan to invade Japan at that time (someone correct me if i'm wrong on this btw)
Anyway..yeah..Logan was often portrayed as someone who fought in WW2.As a matter of fact, one of my fav Wolverine story EVER is from issue 34. If they ever decide to show Logan fighting in the WW2 again, they should chose that scene where he charged an SS batallion with nothing but a knife!