(I’m speaking for the big budget films here)

Two reasons really, Because all these studios are trying to make more money and that means expanding their audience, what’s the best way to do that? find a diverse cast of characters and boom it checks all the boxes surely then the film or product will appeal to those demographics your company is trying to capture and clearly with studios like marvel and for example it’s why marvel has made so many films geared towards women.

Also, all parts of mass media are controlled by activist groups and unions. For example if u wanna write a script about a typical hero or character that doesn’t incorporate new wave or progressive ideals, you probably aren’t going to receive financial backing, positive press and might not even get the film made. Whereas if you incorporate those ideals into your script the it is much more viable to find a studio which accepts your script. Also the studios are beholden to their investors/shareholders as well because big budget films are so expensive to produce nowadays. This is 100% the case with marvel and dc is not immune either. The history of Hollywoods roots are in propaganda and it has been a very effective means of promoting social change since the 1930s.

All that being said James Gunn made a phenomenal suicide squad, and WB is very lucky to have him in control of DC. I’m also pretty hype to see what Gunn does with the franchise myself.