The reason why I do think it's a problem is because when Hollywood shows a trans* character, they are basically saying "this is what you look like, this is what you act like, and this is how other people see you."
After Transparent aired, there were a couple people here who came distressed because of fears of "is this really the best that I'm going to look, or sound, or be perceived?" A cis actor can play a trans person with all of the emotional perfection in the world, but at the end of the day they're still just a man dressing up as a woman, or vice versa. Does the disabled community really care if a disabled character looks completely disabled in the movie? Does it affect their self-esteem? Probably not. But does it matter for trans people. Looking visually NOT like our birth sex is a big deal for us. So by constantly getting members of our birth sex to play our identity gender, Hollywood is subtley constantly sending the message "you are just a man/woman who dresses like your preferred gender. This is you." And it is a problem, because it leads to a distorted perception of what trans people actually look, sound, and act like.
If passability wasn't such a big deal, this likewise wouldn't be a big deal. But coming from someone who stayed closeted for TEN YEARS specifically because I never saw a realistic portrayal of a trans person, because I was constantly inundated with the "man in a dress" image of trans people, I feel pretty strongly about this... letting actual trans people show and tell their own stories, ACCURATE portrayals, instead of constantly sending the message to us that we're only dressing up as our identity gender.
