You're right - much has changed - but the fact that the country is the UNITED States of America has not - one country, one language, one allegiance, one flag. It is a privilege to become an American citizen. To become an American citizen it is my DUTY to learn the language, laws and customs of my new country. Just as if I decided I was going to live and become a citizen of Spain - I would learn the language, laws and customs - I would not expect everyone to cater to me because I didn't respect my new country enough to become a full citizen.
Luckily, there are more differences between the United States and Spain than just that - America is great BECAUSE of the Melting Pot, not in spite of it.