People are too damn sensitive. Political correctness is the enemy of humor. Especially when it's taken to the extreme.
In fact, some disabled people use their set-backs to make people laugh. They realize they make normal things funny and use that to bring people joy. There are many movies with handicapped people doing hilarious things. Little people also use their shortcomings (oops... no pun intended) for hilarity.
They can't change it, why cry about it?