Making diversity a priority is an artificial obstruction to the creative process. When you set out to make high-ranking female characters instead of just characters you've compromised the creative process.
Absolutely, and I've experienced it myself as a poor struggling writer
But it's something an author has to do regardless. Most authors don't want their own prejudices informing their stories; I think most want to create vibrant worlds and characters that all readers will enjoy. But if, for example, you're a white person like me, you may finish the first draft of your story and realize there are no people of color in the story AT ALL.
For me, that's a problem. Yes, I rethought the world I had created. Can people of color exist in this world? If not, I want to make it so they can and that it makes sense. Can any of my main characters be people of color? Let's see how I can work that in as naturally as possible. It also forced me to self-examine why I had created a world full of white people in the first place. Clearly, on a subconscious level, white is default for me.
Writing constantly shifts between the creative and the critical. Otherwise, authors would simply spew out "spur of the moment" nonsensical bursts of creativity. The critic has to push the artist aside and examine the work with narrowed eyes, not just for content, but grammar, structure, pacing, etc. It should SEEM easy and effortless to the reader, but for the writer, it never is (unless you're a genius!)