Leaving Japan alone in 1917 actually made sense...
Did leaving japan alone in the 30s after it was caught arming Canadian rebels, after it torpedoed a US carrier, and after it bombed the US mainland make "sense"?
I think you need to keep in mind however that Japan switched sides at the end of WW2 and started attacking Britain and forcing Russia out of Vladivostok. Why would Germany and the US attack an "ally" in a region that doesn't really affect or matter to them?
That's the situation in 1944. In the Great War, Japan is an ally of Russia and the 1930s Japan arms Canadian rebels, torpedoes US warships, and bombs Los Angeles.
Got an excuse for ignoring Japan then?