Well, it has to do with the culture. Japanese TV can be a lot more graphic, but at the same time, they don't really have too many shows like Law&Order and so on because their crime isn't such a problem compared to the United State's. So the quality of programming is different.
Their cartoons are more serious and carry morals and so on... Characters in their cartoons die, male characters cry, and more serious issues can pop up. Even though Sailor Moon is a kid show, their were lesbians in it. Now, for Japan, the audience can (for the most part), be alright with that, but America's audience isn't used to that sort of thing in their cartoons. InuYasha is also a child's show, but since their is blood, some death, and some sexual content, it's seen as a show for an older audience... The dialog is often dumbed down in dubs, due to the idea that people aren't supposed to think when watching cartoons as well.