Cartoons are a good tool to teach morality, by tool, i mean one resource that should be used but not the only resource. Cartoons are made for the entertainment of kids, kids and people in general have a very easy time deriving values and morals from something they enjoy, cartoons being such, and cartoons (at least, ones of nickelodeon and cartoon network, anything on the likes of comedy central is meant for teens which have already developed their morales) are often very deliberate in showing right from wrong. Pop in an episode of the fairly oddparents (The name was something like that) and watch it to the end, guaranteed the episode will be based around one morale issue (cheating, lying, stealing) and in the end, timmy (the protagonist) will somehow get in trouble for breaking a morale which was very obvious in his situation, but in the end, timmy will pretty much always say he was wrong for doing X and will never do X again, it is very effective purely because situations like this are very entertaining to children.
Now, some people will say this isn't effective or it should be a parent's responsibility, but, there is a good reason why such cartoons have lasted for so long, no person is perfect, some people have more morale's than others, and it is very common for people to teach not only their good morale's and values, but negative morale's and values (racism, stealing, ect.) If only the parents were teaching kids these things, then every kid would be almost identical to their parents in there values and belief in right and wrong.
Dre: you pointed out that people who make cartoons, like people in the media, don't have the authority to teach values, but what gives other people parents more right to teach values? There are parents who have stolen, killed, are racist, ect. there are also people in the media who have done that stuff.
Also, Dre, you picked an over-exaggerated example, no cartoon will teach a child it is morally correct for a boy to dress up as a girl and kiss other boys, a cartoon may do it for the attempt of comedy, but, cartoons have always made it clear in some way that a child shouldn't do that, normally by showing how comedic it is.
Some kids have maturity, some don't, some are brats, some aren't, all kids cannot be generalized like that, because there are just as many who are brats and immature as there are mature nice children
/ends rant