I'm not saying that. But I also never had a problem with anyone making the films. It's about the story. If a character is black and female then cast for that. But to create something in order to JUST fill the "we need a black and female character" is the wrong approach
When William Moulton Marston was tasked with creating a new superhero to employ the educational potential he saw in the medium of comics, his wife Elizabeth told him to make it a female superhero. That character they (and William's mistress Olivia) co-created is Wonder Woman, and she comes directly from the kind of thinking you denounce here. Because, for a creator, often the message comes first.
Or as a different example, a few months back I bought an artbook by Boris Vallejo, and I found this piece called
My first thought upon seeing this was "This looks cool." My second thought was "Looks like Black Conan". And the combined third thought was "Black Conan would actually be pretty cool."
It started me thinking that most of our western fantasy is based on European myths and legends (with some North-African myths sprayed in, but through a more old-time European-centric lense, like Evil Mummies and such). Now, Asians have their own fantasy literature and movies and such dealing with Asian myths and legends.
But I'm not aware of much fantasy based on African myths and legends. If there is, it's not made its way to me. I've seen some use of Anansi, and originally zombies (not the brain-eating kind, the original kind) are based on some African cultures' rituals, but otherwise I haven't even heard much about African legends and folklore. And my guess is I'm not the only one who's mostly ignorant of African stories.
But there must be stories, obviously, it's a large continent with many different cultures dating back at least as far as the European cultures. And they can't all have been suppressed by European colonialists, as the legends of Egypt, Arabia, India, have survived colonialism. There must be a treasure-trove of myths that could be a great foundation for fantasy stories. So, yeah, Black Conan would definitely be cool.
What I'm trying to say is, if you change the gender and/or ethnicity of your main character, it not only gives people of that gender and/or ethnicity some much needed identification and validation, it also can change the perspective from which the story comes from, and that enriches all of us, including a white, heterosexual cis-male like me.