Cultural Integration and differences

I was reading another topic yesterday about TV, Cartoons, and what people let their children watch. I saw a comment from a poster who said they refuse to let their children watch "Dora the Explorer" because she speaks Spanish during the cartoon. That poster's comment paraphrased was "This is a America--speak it!"
Now, have we become such a society that we cannot accept differences between people? I mean, why is America called "The Melting Pot" anyway, if we can't accept the fact that other cultures exist? That was how this country was founded, right?
Now, I understand frustrations about not being able to communicate with people that speak different languages. That's why shows like dora, dragontales, and even sesame street are so important. Children need to know that these differences exist, don't they?
I am not looking to start a who's right discussion or a racial discussion, but I would like to know how others perceive how we, as a nation, feel about different cultures.