This.

I work for Prudential as a field worker and I work with a girl with down syndrome, who happens to be the daughter of one of my mother's long time friends. Seeing the fandom's reaction, what little I've seen of it, about the change in Derpy's voice makes me sick. And you're absolutely right, people with disabilities aren't always happy. They get frustrated, especially when they cant convey their feelings.
Everything you typed are my exact feelings on this matter.