Hey, it's not all white dudes! Isn't that swell. Yay, diversity! You did it, slugger. You're progressive now, and you no longer have to worry about any pesky nerds clambering into your Twitter replies to tell you that you're clueless. The Law of the Office Stock Photo dictates that people should be happy just because diversity is there on the surface level. Hell, it happens in comic book movies, too. "The Avengers has Black Widow. And she's a lady. So you can hush up because ... she's a lady."
But before you can pat yourself on the back about the fact that you're hip to the hot new trend of being a decent person, ask yourself this: How many stories does she get? And not just stories that include her, but stories that are about her? How many stories are definitively hers? Sure, Marvel has given her some plots, but they're always located in the asshole of the larger narrative about invading aliens or killer robots or some shit. And that's why telling people that "Hey, be satisfied, because there's a black guy on the team. You got what you wanted" is a dick move. That's not diversity.
Walt Disney Studios Motion Pictures
"If five minutes of Black Widow and two hours of Captain America won't make you leave us alone, we don't know what will."
Diversity is peoples' experiences. Diversity is listening to stories that encapsulate what it's like to be someone who isn't like you. Diversity isn't mixing and matching skin tones in the hopes that if you get the ratio right, the internet will get off your case. People can see through that shit, and they won't buy into it. Diversity requires getting writers with unique perspectives who can tell unique stories.