I feel that many of the politically correct crowd uses political correctness as an empowerment tool.
It is part of human nature to want to feel superior to others, or, lacking that, to have power over others. It is why, in part, you have those who feel compelled to purchase very expensive cars: it is a status symbol. It says I have more wealth than you and so I have a higher social standing than you because I am driving a Mercedes Benz and you are driving a Honda.
Others seek power over others. Some seek that power through politics. Others seek power through wealth or social status. Others seek power through controlling the thoughts of others.
By controlling thoughts I mean simply this: if I can persuade you, through shame, social pressure, even legislation, to not utter certain words, then I have succeeded, at least to a small degree, in controlling your thoughts and perhaps even behavior. That is power over you. You no longer have the powered to use those words I have prohibited you from using. You may wish to use those words in communicating with others, but I have succeeded in forcing you to use alternative words of my choosing. If that is not seeking power over another, I would like to know what it is.
Certain organizations are famous for seeking to control thoughts and behaviors of others. For instance, there are animal rights organizations that have sought, through legislation, to prevent people from calling the cats and dogs they own pets. Rather, these groups wish the term animal companion to be used, or some like phrase.
Words do have power. If you can succeed in preventing a person from using a word or phrase you do not approve of then you have succeeded, in a small measure, in establishing power over that person. The converse is true also, of course: people use words to empower themselves over others.
A good example is the n word. As you know, The Adventures of Huckleberry Finn by Mark Twain has often been banned in school libraries due to the use of this word within the text. Yet, as Twain himself has pointed out, during the days of slavery this word was commonly used by all: whites and blacks (for purposes of this posting I am simply going to use the terms whites and blacks rather than spell out African-American, etc). It was not considered a particularly derogatory word during the times of slavery. Why? Well, I guess because whites had utter and complete power over black slaves. Slaves had absolutely no power whatsoever, and so, in a way, it would have been superfluous for the n word to be derogatory to slaves.
However, during the Civil War some slaves gained their freedom, while the remainder achieved freedom at the end of the war. Blacks were now gaining power. True, it was not much power, but it was a start. As the decades rolled on blacks gained more and more power, such as the right to own property, demand wages for employment, to vote, etc. As they gained power the whites saw their power over blacks ever decreasing. Hence in time the n word became a power word, used by whites towards blacks as a in an attempt to keep some form of social dominance over them; for the whites to continue to feel superior. As blacks achieved power, so the offensiveness of the n word increased, both in meaning by the whites and acceptance by the blacks.
Indeed, when blacks gained total legal and social equality to whites, then the n word probably achieved it highest point of offensiveness as whites used the term in the most derogatory sense in an attempt to maintain some type of feeling of superiority.
We have seen over the past decade or so the n word used more and more by blacks, possibly as an attempt to wrest the power of that word away from the whites, or possibly (in individual circumstances) used by a black to another black to indicate the users superiority over the other. After all, whites have always used words, symbols, etc., to try to show their superiority over other whites.
It is always interesting to see what words will be declared politically incorrect by some individual or group. The attempt to outlaw the word pets, when applied to animals, has thus far been unsuccessful. Yet I have no doubt that the attempt will continue to be made. Of course, many of the words that people seek to send to the scrapheap of linguistic history deserve such a fate, such as the n word. Others feel that some words, such as mentally ********, have themselves become power words used by people in an attempt to keep down the subject of the words. After all, the term mentally ******** not only has a medical meaning, it also has a legal meaning. Historically, if one were declared mentally ******** then that person suddenly found himself deprived of certain legal rights enjoyed by others, such as entering into contracts or even marriage. To be called mentally ******** continues to have legal as well as social significance.
In conclusion: I certainly feel that there are many valid reasons for some words to no longer be used, particularly in certain situations (such as, to a persons face). Of course, one must recognize that many seek to have words prohibited simply as a basis for exercising some form of thought control over people. It is a fine line to distinguish the good from bad.