People are sensitive. Common words that are used to describe people have suddenly been given a new, underlying meaning of 'you are lesser'. Oftentimes it's not the word itself, but the tone in which it's said. Take 'minor' for example. A minor would perceive that label as offensive if you said it to debunk his/her argument. A minor would engage in a conversation of being unable to drive with the reasoning - "I'm not old enough yet." You could see words as positive or negative only when someone comes along and uses it. Fat used to be adjective, but somehow in today's day and age - or when you got older - it's now a dirty word.
So when you say someone is handicapped, according to today's logic, you're telling them they're imperfect. And that's a bad thing.
