What is it that makes Japanese animation popular, not only to the young but to adults as well? I remember a few years ago when I was a freshmen and sophomore in university I was addicted to the Japanese anime "Dragon Ball Z" super dragon ball heroes episode 6. In fact, it even gave the famous American cartoon "The Simpsons" a run for its money in my book.
What I find odd is that "Dragon Ball Z" has about 39 episodes per season but if you want to write an overview of the entire season you can do so in just about one paragraph. And I mean you can add all the meat of the entire season into just that one paragraph. Here is basically what I mean...
Episode 1-10ish: Bad guy arrives and starts terrorizing the fictional planet. Minor super heroes fight the villain and lose (perhaps one even dies). Main hero who was conveniently not able to combat said villain for whatever reason finally arrives for the ultimate showdown. Episode 10ish - 38: Half of the time verbal fists are being thrown between said hero and villain while the other half goes to physical fists. Sprinkle in some dialogue from the minor heroes like, "Wow! He is at full power!", and you have yourself about 600 minutes. Episode 38 ending: Hero kills villain. Episode 39: Everyone is happy and life returns to normal.
And there I was, in my late teens, with my eyes glued to the television. I even knew nothing of importance was going to happen for about 25 episodes but there I sat unable and unwilling to move. "Dragon Ball Z", which aired in Japan from 1989 - 1996 did not first air in America until 1996. By the time I started watching this anime it was already 10 years old. And this length of time for an animated series is a long time when compared to the new techniques and styles of animated characters. But "Dragon Ball Z" was at the top of the charts for a cartoon series for its duration in America.
So back to the original question, what makes Japanese animation so popular? It may be this humble author's opinion but I would have to say the action, and to a further extent the deadly violence. As a prime example "The Simpsons" being probably the most popular America cartoon is a comedy based cartoon dragon ball heroes episode 6. In fact most of the newer American cartoons are based on comedy or to some extent mystery (Yes, Scooby Doo, I am looking at you).
In the 1980's America had its share of action cartoons like "Transformers", "Thunder Cats" and "He-Man" but as the end of the 80's came so did most of the American action cartoons. And with the release of the great "Akira" on video in 1990 and the subsequent mind blowing action/gore that came with it, most American cartoon lovers immediately turned their eyes to Japan. The movie stuck its "geta" in the door and made the debut for Japanese animation in the west.
In the 1990's newer American cartoons such as "Batman" and "Superman" came out and were enjoyed by most American action cartoon lovers, but with only these few American cartoons there left a lot of time for other action animation from Japan to fill the gap. With the amount of older Japanese anime being translated along with Japan's fresh anime, there is quite a lot of the Japanese component in the western market. So, this author's opinion is that Japanese anime happened to come along to the west at just the right time, and now that it's here it won't be leaving anytime soon.