That's almost certainly it. They're afraid of losing the middle aged crowd and young male audience with Wonder Woman (you know, the audience that they've got by the metaphorical balls with Batman, Superman, etc) because god forbid they appeal to another demographic. But with how WW84 was derided for being, well, more in line with her character, I don't think we'll be seeing Warrior Woman take a break for much longer.
It's a shame. Diana absolutely can play up her Disney Princess elements and still absolutely kick ass with the best of them. It's strange. They're afraid of losing guys too insecure in their masculinity to embrace the totality of Diana's character-- they're literally afraid of losing the very people Diana was created to combat. The same crowd who can't appreciate that Batman: The Brave and the Bold was flippin' awesome. What.