They've tried it in other well-established entertainment media, with mixed success.
D'you know that cartoon "For Better or For Worse", in the comics section of newspapers? The artist made one of the characters on there come out to his parents and friends (in the comic), and the reader base was so outraged that she (the artist) recieved hatemail and even death threats as a result of this. It wasn't as if he was dressing like a flamer or anything - he just came out and suddenly everyone is working themselves into a froth over it. Over a character that DOES NOT EXIST IN REAL LIFE.
Admittedly, the cartoon in question was one of those more serious, adult-humor cartoons, but still, IT'S A CARTOON, for crying out loud. Whoever makes the first cartoon or live action show for kids that features a obvious platonic homosexual relationship is going to have some serious balls, which is commendable, but for their sake I hope they have better lawyers than anything, because of the horde of parents wanting to take their show off the air.