I concur with the posts above. I find that fewer and fewer of my students (of all races and ethnicities) truly want to use standard English in their speaking and writing. When we read Shakespeare (which is not standard English now), my students struggle immensely because they don't even possess the standard English skills to be able to comprehend Shakespeare's much more difficult language. They want summaries and modern forms of everything instead of seeking ways to challenge their comprehension and analytical skills.
This applies to my AP students as well who don't understand why they cannot write for the AP exam as they speak in everyday life.
I agree with all posts here. It's important for ALL people, not just "ethnic groups", to be able to speak, read, and write standard English, at least in the United States. I can't count the number of times I've impressed upon my students the importance of speaking well. It can really influence a first impression, particularly when interviewing for a job, scholarship, etc. And nothing irritates me more than to hear political, economic, and social leaders speaking as though they've never read a book. Despite my best attempts to "refudiate" this habit in my students, some maintain that casual tone in their writing as well. I'm rather concerned about the influence of texting and Twitter on speaking and writing, since people are limited in both methods of communication, yet so many people use them as their mediums of choice in speaking to others.
I guess I deviated from the idea of ethnic groups specifically, but I really do think it's something important for everyone. Of course, no one should be discouraged from speaking their native language. But it is vital to be able to communicate in standard English in order to be successful in the United States.
I agree with all my colleagues and only have one idea to add. In America, Standard English is the language of law, business, and education. That means in order to be successful in those three arenas, one must be able to speak appropriate, standard English. How any group, ethnic or otherwise, speaks in other circumstances is up to them--as long as they are able to be understood. When I travel internationally, I always try to speak enough of the language to conduct minor business transactions. I must admit, hearing any group of people speaking a language I don't understand is a bit disconcerting--especially if it's here in the United States. In general, though, this inspires me to improve my foreign language skills, and that's a benefit in every way.
The previous posts were quite strong. Ethnic groups should possess a functional understanding of standard English in order to have more opportunities open to them in American society and increase their social, economic, and political expressions of autonomy. At the same time, maintaining their own native dialects is extremely important. Literature does reflect this. For example, in Richard Rodriguez's "Hunger of Memory," he details how the nuns at his Catholic School instructed the parents to speak English at home in order for their children to become more fluent. As a result of doing so, dialogue in their own native language decreased and less conversation, less moments of natural intimacy became apparent. I can also concur with this. One of the worst things about being a child of the 1980s was the belief in the "melting pot," an assimilationist theory that stressed that immigrants should try to "blend in" with Americans and forego their own natural and ethnic identity. This included surrendering native language to English, creating such a schism in the children of such backgrounds that the issue of race and cultural identity was further convoluted. I think that language, in general, is a vague medium to express emotions, experiences, and narratives. The more knowledge of languages that one possesses, the greater the chance that this accuracy will increase, so knowledge of both native languages and English can increase the chance of being accurate and precise in a domain where such elements are difficult to obtain.
In my opinion, this depends on the context. I think that it is extremely important for all ethnic groups (in the United States, at least) to be able to speak standard English when they are in a setting where that is appropriate. If they are not able to, they will not be able to get good jobs, etc. However, when they are in informal settings, there is no reason why they should not use non-standard English.
As an example of this, I tend to think about the "pidgin" that is used in Hawaii. When I lived there, my friends and I used that dialect (linguists say it is a separate language) when we were together. That made sense because there was no need to sound educated. But in school, we used standard English. This was necessary because we would need to use that kind of English in formal settings such as job interviews and most work places.
There has been a great deal of research in this area and my conclusion is that ethnic groups must speak standard English along with their personal dialects. It is like a second language, one for the job and one for home and friends. Just look at television news and the standard for those delivering the news. Even in rural areas where people speak in a country dialect the local news is delivered in standard English. In a courtroom or a doctor's office all of the staff is required to speak standard English. Ethnic groups are encouraged to keep their cultural identiy but there must be a standard for English in the professional community .