As a person who uses a wheelchair for mobility, I think I have a perspective on this that the general able-bodied public may not realize.
I think Rain Man was a brilliant movie with a lot of love and compassion in it as you got to know Raymond at the same time his brother did. Getting to know someone with autism or autism spectrum can be extremely challenging. This movie shows how challenging it is and shows the horrible discomfort Raymond contends with in each new situation. I have no complaints about this movie. I have the highest respect for Dustin Hoffman as an actor, largely because of this movie.
The Big Bang Theory is very funny and quite intellectual without being obnoxiously overbearing or superior to people with average or lower intellects. I think that is meant to be the point of the show; to demonstrate the humanity of highly intelligent individuals, dealing with the same problems of everyday joes and having to work hard for things just like the rest of us. We are all quirky in our own way. Whether or not Sheldon is an Aspie is not mentioned because it's not really relevant here. If you want to make it about that, then of course you could say that they are mocking Aspies. I don't agree and I have several very good Aspie friends. I have never met an Autistic person who was stupid. Never. They tend to be phenomenally gifted in some way and excel at expressing themselves in THAT way. They are usually very socially awkward, some more than others. In any case, all of them, without exception LOVE Sheldon and the Big Bang Theory. Perhaps they relate and recognize that he's an Aspie too. One thing that Sheldon has overcome that many Aspies strive for is to be seen as an intelligent and thinking human being. No one doubts the brilliance of Sheldon's mind. They just realize that he's socially retarded. He is relatable for many of us, not just Aspies. So, again, I don't really have complaints about this show.
Having said all that, I think it is absolutely wonderful when an actual disabled person is given the opportunity to portray someone with a disability of some sort. I also think this extends to other issues that may not be considered a disability, but perhaps a social vision of what is acceptable might be challenged. People who are transgender or gay or fat or very short or very tall...all of that is, for the most part, poorly or mis-represented in entertainment. I admired the program Glee for their efforts in this area. Major characters were gay, in a wheelchair, overweight, rich, poor, transgender, had parents who were gay, and had Down's Syndrome! They were brilliant for their efforts to make a cast that really was a mix of issues, just like society! Every character had a voice and a way to express themselves! I suspect a lot of that was missed on the typical viewer, who were mostly teens, but it was a great step forward!
So, I see all these efforts to bring attention to people with disabilities or social challenges as a step in the right direction. I would hope this would lead to more employment opportunities for people contending with such issues. There are a lot of people with challenges rather than disabilities or inabilities and who have a great deal to offer.