Good question. Sometimes these terms come from a medical background and people do not like to be medicalized. Sometimes the terms are too narrow, eg not all disabilities are crippling. Sometimes these terms are exonyms and people do not like them. Sometimes the words change meaning over time.
And sometimes we return to them. Queer is a label I use for myself that's a reclaimed slur. I know plenty of gay men who call themselves fags. Some disabled people use "crip" as a term of endearment. But usually these reclaimed slurs are for the exclusive use of the members of the community internally.
It just seems so futile to have to keep coming up with new words for the same thing, when the new words will inevitably become slurs in the same way, at least if anyone uses them. So it's not like we can avoid the offence, it is just transferred to a new word. Wouldn't it be better to accept that some people will say mean things, and focus on learning to live with that, and on making people be less mean?