I totally agree with you. In the movies, people with any kind of mental illness are often portrayed as completely out of touch or else dangerously homicidal. I get so sick of it. No wonder no one wants to admit to DID or anything else for that matter.
I am still haunted by "What's real and what isn't?" questions. No one close to me has even 1/10th the doubts I have, and it's because of crap like you describe. I have to tune it out or it sends me over the edge.