I agree, especially when it comes to transgender people. They're too rare to expect every transgender character to be played by an actual trans person - it might be very difficult to find one with the appearance the writer/director had in mind.
I THINK SPECIFIC INCLUSION CASTING IN MOVIES IS STUPID. ACTORS SHOULD BE CHOSEN FOR THEIR SKILL AND HOW THEY FIT THEIR ROLE, NOT IF THEY'RE THE FIRST OF THEIR GROUP OR NATIONALITY IN A MAJOR ROLE.