People with developmental disabilities have suffered far too many historical and contemporary prejudices to have it be added to by people who should know better.
Even the former clinical references to people with developmental disabilities are preferred (precisely because they no longer carry the clinical impact of referring to a set group of identifiable people). You know: "defectives", lunatics, imbeciles, idiots, deviants, "distracted persons", non compos mentis, and the like.
It is doubly ironic that the word is used in political strategy contexts because people with developmental disabilities tend to vote Democratic (although many of their staunchest political allies are Republicans). 13 million people with a wide variety of disabilities voted.
I will avoid in engaging in lengthy proleptics but I must say that I am not "overly sensitive" on the matter. The use of "retarded" by at least two people on this list was unequivocally negative and offensive. The fact that this insensitivity dovetails with all of the ugly prejudices against people with disabilities (as sick, subhuman, menace, burden, object of pity, etc.) should be disturbing to all on this list.
Peace,
Jim
"There are no class of persons in our whole population who, unit for unit, are so dangerous or so expensive to the state. This excepts no class, not even the violently insane. They are much more dangerous and expensive than the ordinary insane or the ordinary feeble-minded or the ordinary male criminal. . . . There is no class of persons who are more fitted and more apt to spread disease and moral evil than these girls"
W. N. Bullard in "State Care of Imbecile Girls" from the *Proceedings of the National Conference of Charities and Correction* (1910)