I understand that people "should" learn to speak standard English--though what that standard should be is up for debate. But I also believe that people whose natural English accent is closer to standard simply by virtue of where they were born or who their parents are "should" try to eliminate their unconcious bias towards those who weren't similarly blessed.  Not everyone has the language talent to eliminate habits they formed over many years of use.

You see the same thing in other languages. Take Chinese for example: People who grew up native standard Mandarin speakers often look down on people whose Mandarin is accented from growing up speaking a different dialect and only learning Mandarin basically as a second language. And now, because authorities have long favored Mandarin, many regional dialects, and the culture to which they are inexorably tied, are slowly eroding in usage. And with goes the regional culture.