think no matter what label is clinically applied to people who are mentally challenged, it will eventually end up being used as a pejorative and become politically incorrect.

Doesn't mean we shouldn't go with what's current. Do you call black people "colored"? I hope not, because it is currently offensive (outside of South Africa where it happens to be the preferred term iirc). But the NAACP still has it in the name!

So what?

The R word is offensive now. "Colored" is offensive now.