In sociological terms, Japanese culture is pretty heavily group-centric while Western culture is pretty heavily indiviudal-centric. A great example of this is advertising. In U.S. commercials things like "rebelling", "not following the crowd", and "being yourself" are very common themes. These things are seen as being positives. In contrast, in Japan "duty" and "belonging to a group" are much more important. Imagine how effective a commercial would be if the gist of it was "Everyone you know is eating this brand of chips, so you should to" - it seems silly to us. Conversely, to them "Everyone you know is eating another brand of chips, eat ours if you want to be different" is just as silly.

Many Western games feature stories that revolve heavily around renegades, people who do things that are considered wrong or illegal by everyone else, but the protagonist knows must be done. These themes are naturally not as popular in Japan. I was born in eastern Europe, which is much more group-centric than the West but not as much as Japan, the differences in what is percieved as important (individual vs group) is pretty large.