Yeah, me, too. But in reality, it's 2015 and there are still many groups of people who cannot turn on mainstream television or go see mainstream movies with people who look like them or have similar backgrounds as they do in it. It's just a fact. However, we often shoot the messenger when it comes to casting. Yes, the Casting Department and producers make final decisions about who you see on the screen. But, writers give them the canvas to begin with and often, it's blank. Well, when you're given a blank campus, you paint it in your color of choice...or leave it blank.
I'm a strong believer that diversity begins with the writer. You are the master of your characters. You fill them out to be whole, well-rounded people... with no identity. We often leave out a huge part of who our characters are when we don't define their ethnic background, nationality (which is not the same as ethnic background. Does this need to be a post of it's own?), and/or sexual orientation. Why does this matter? We live in a color blind society. Well, God bless you if you're one of the people who is privileged enough to live in a place filled with pastels that no one sees. But in America, everything that we are matters. Everything that we are is judged. Everything that we are makes us who we are. It can't be left off the page.
For example, a first generation American's story is not that of a 3rd generation American. An immigrant's story is not that of a Southerner who's ancestors fought in the wars. A person of color's story is not that of the next person of color because being Dominican vs Jamaican vs Cambodian vs plain ol' African American means a different way of life for each ethnicity, especially in America.
Characterization is a job of the writer just as much as location description. For example, a good writer wouldn't place his/her characters in simply a house, a kitchen, or a bedroom. The details of the location paint a richer character. If the character lives in a rundown home, then we know she either doesn't come from money or once had it but it has been taken away by possibly something she's done. Now, the audience is intrigued. The audience wants to know more. If the character's money was taken from the her, she now seeks vengeance. Ooo... this story just got good. And guess what, we got all of that out of one word "rundown." So imagine how much your audience will get from knowing what your character looks like, where he/she is from, what religious beliefs she has... the list goes on.
At the end of the day, we (as writers) can continue to pass on blank canvases to Casting Directors and allow our audiences to constantly shoot the messenger. Or we can man up and make real character choices when writing. Don't let diversity give you anxiety or make you think you're obligated to submit to some status quo. There are a lot of TV Networks that answer to Diversity Execs about in-front-of and behind-the camera diversity hires. But eff them. You're writing the story. And just as much as your story should reflect the world, so should your characters. Our world isn't blank. It is filled with color. So write that way. Nuff said.