Well, look at it this way - WW2 was a great part of Japanese history, the thing that shaped Japan as it is today, the thing that broke and reforge japanese as nation. And out of thousands and thousands of anime titles we have less then 10 anime talking about, or even taking place at the same time as ww2.
I can think of only one explanation to it - not surprisingly, japanese teens are not interested in history, even if it is a history of their own country.
Now, how much a japanese viewer would be interested in a war that raged thousands miles away from his dear country? I think not interested at all.
History does not make money, moeblobs do.