building on the first post about accents...
Accents aren't just some passive attribute we have, like the shape of our nose. We choose them, whether consciously or subconsciously. Of course, we acquire an accent along with the language we acquire, of whatever region, social class, ethnicity, and so on. That accent represents our language variety, where we grew up, with whom we grew up, how we grew up, etc. Interestingly, it seems that our peer groups growing up have a greater influence than our parents. My younger brother, who grew up with the same parents in the same place I did, pronounces several words differently (and worse, in my opinion!).
But we also choose our accents--accommodating to others of different accents, emphasizing differences, and so on. Our accents are part of our identity. I am from the Midwest. I have a Midwest accent. I love my Midwest accent. I do not love some accents from, say, Texas. I do not pick up that accent. I am not a Texan. Ditto Brooklyn. Ditto Alabama. My accent is a large part of who I am and I don't want to be anyone else.
Accents as identifiers are not likely to disappear. We may listen to the same somewhat unmarked, standard variety on TV or in movies, but our identity lies more with our communities, our families, our friends.
Accents may also reveal a non-native speaker. Someone who has learned English later in life will likely have an accent. The fine motor skills needed to pronounce our language have been fine tuned for years, and our attempts to pronounce another language are often influenced by our difficulty in re-learning those fine motor skills. Infants can recognize virtually any human language sound, but as they acquire the language in their environment, they lost this ability and focus/maintain only those sounds needed for their language. Children growing up in bilingual or multilingual environments acquire distinct languages and accents without much difficulty, thus developing the fine motor skills needed for each language. As a point of interest, children can acquire sign language before spoken because the motor skills needed are not as difficult as the vocal tract.
While it may be difficult to acquire a native accent in a second language, it is not impossible. We know people who have done so. It doesn't have to be inevitable.
But if our accent presents a part of our identity, perhaps we want to keep that accent. A person who speaks English with a Spanish accent may want to maintain it, because that is part of their identity--a Spanish speaker who can also speak English. Where's the fun in sounding like native speakers and disguising a major part of who we are? This choice may be unconscious or not, Most of us don't spend a lot of time analyzing our pronunciation, after all.
Yet there are people who would prefer to change their accent. Called accent reduction, the individual undergoes training to deliberately change their pronunciation. In the past, if you wanted to be a TV news journalist, you might want to drop obvious regionalisms so that you'd be more employable. Or an individual dislikes how others react--thinking the Southerner is stupid, for example. Second language learners may aspire to diplomatic or international positions and want to less their first language accent.
Apart from these perfectly valid reasons, most applied linguists and English as a Second Language teachers don't expect or ask learners to sound like native speakers. It's not usually worth the time and effort involved, particularly when there is vocabulary and syntax and pragmatics to work on. Instead, we strive for our learners to be understandable and to not be stigmatized by a particular pronunciation. "Understandable" is tricky because how is one teacher to determine what other audiences will find understandable? And most teachers have experience with accents and understand easily while someone without any diverse exposure might find even a small shift difficult to understand. That being said, it's still our goal.
The issue of stigmatizing is important, because we don't want our learners to be judged wrongly on the basis of their accents. Native Spanish speakers often have difficulty with the English sound represented by "th", as in "they" and "think", substituting [d] and [t] respectively. So the person might say "day are going to school" or "I tink you are right"....and the native speaker thinks um.....Black English, south Baltimore, baby talk....and that forms their opinions of the speaker. So the goal is to be understandable AND work on sounds that might be stigmatizing.
Sometimes we focus so much on the difficult sounds--r, th, w/y, some vowels--that speakers hypercorrect themselves. Suddenly the Spanish speaker, who can say "sheet" perfectly well, begins saying "shit". Well, that's obviously not optimal....we want the focus on the message, not on how it is said. So that is another issue we keep in mind.
US Americans, Anglos, are not very tolerant of accents. Not understanding where they come from or how they relate to a community, Anglos tend to judge people based on how they sound. There are many non-native speakers who wish they spoke with native accents....but why? Accents are rich, contextual, informative, creative, unique, and lively. They are expressions of who we are, and we should celebrate that.