The one line (among a few) that I really hate getting, and have gotten on a handful of occasions, is "You'll never change".
Despite all the progress I've made, and that many of Aspies have made as a collective, it still doesn't seem "good enough". Like their goal is to "cure" or "convert" us to the mainstream and if we show even a trace of deviation, then we're not going to change.
Well, on a fundamental level, it is true that our "Aspie program" will not change, but our coping mechanisms and strategies can, and must be practiced regularly to become more natural or as natural as possible w/o getting stressed out. So that to me is a change of attitude and a change of approach, even if it doesn't change our fundamental program. However, I sense that many NTs won't see it that way, or they will see us as over-complicating things, which sucks.
Also part of this comment may be based on our lack of intuitive ability to be able to abstract applied rules of conduct from one context or setting to a similar context or setting. We do it well in one setting, but in another, fall short of expectations that "it was obvious if you did A in X situation, you should also do A in Y situation. You'll never change, you never learn."
So, definitely a comment that I find insulting and trivializing. To me, the kind of people that will never change are hardened criminals on parole, drug addicts, and adult bullies in the workplace. I don't put myself into that kind of "don't change" category. And neither should any other person with Aspergers.