Eugene Volokh has an excellent post on the use of terms that might be regarded as offensive. Three paragraphs struck me as offering an interesting argument, one I haven't thought through very carefully yet, but one that nonetheless intrigues me:
If handicapped people learn that some people say "disabled" and others say "handicapped," and that neither is evidence of hostility, a few might still bristle at one (or the other); but many will be satisfied by the explanation that decent people use both. But say that everyone is told that "disabled" is the one right term, and some decent people don't go along, whether because of force of habit, strong preference for "handicapped," or just bristling at being told what to say. Then handicapped people who hear the term may well become more offended, because they've been taught that the word is offensive.
People who might even prefer to shrug the term off might feel almost obligated to take it as an insult. If someone calls me "Gene" rather than "Eugene," I'm a little annoyed (that's just not the name I prefer in English), but I assume that it's just because they've fallen into that habit with other Eugenes they know, who do go by Gene in a way that I don't. I assume the speaker's intentions were good, and I think I'm happier for it.
But if someone started a campaign of insisting that calling me Gene is actually rude, perhaps even insulting (because the diminutive implies a diminution of my status), I'd both hear "Gene" a bit less often, and be much more annoyed when I do hear it, precisely because I'll worry that it's a deliberate violation of the New Good Manners Rule and thus a deliberate slight. Those who make the handicapped/disabled issue into a matter of identity politics rather than just a matter of apricot/apricot (or even Gene/Eugene) may thus increase the amount of hurt feelings on both sides.