To Westerners, it's subtle, but you have to consider it from the Japanese POV. There are still mainstream elements in Japan who deny responsibility for the war. This is part of why a lot of other Asians are still very worked up about it. Note this comment of the director (from Wiki):
However, director Isao Takahata repeatedly denied that the film was an anti-war anime. In his own words, "[The film] is not at all an anti-war anime and contains absolutely no such message." Instead, Takahata had intended to convey an image of the brother and sister living a failed life due to isolation from society and invoke sympathy particularly in people in their teens and twenties, whom he felt needed to straighten up and respect their elders for the pain and suffering they had experienced during arguably the darkest point in Japan's history.
This could be seen in terms of trying to rehabilitate the image of the people who were around during the war. However, I haven't seen the full text of the interview, so I don't know what else he said. Again, this is just one view that I find interesting to consider.