Oh, come ON!
It’s extremely stupid to say that this is Naoko’s fault for not creating anything new. They could’ve just adapted the Princess Kaguya manga if they needed material THAT badly, or the side stories that haven’t been adapted yet. I just find it a very thin excuse and honestly, a bit misogynistic, to put the blame on the author when Toei is infamous for being ****** with their anime. It isn’t being prioritized and that’s certainly the true reason why we haven’t had anything come out yet.
As much as i agree we can blame Toei for the quality and their priorities i dont think we can blame them for creating new material. Im pretty sure they cant do anything without Naoko's permision. At the end of the day they created several different versions of SM universe so at least they've shown interest in keeping the franchise alive.
They already adapted Kaguya in the S movie and doing it again wouldnt accomplish much and would hardly feel new.
The remaining unadapted side stories are all one shot side stories (2 more exam battles, 2 more Chibiusa diaries, Casablanca memories and Paralell SM)
And as much i would LOVE to see Sailor V anime i can see why they might think it wouldnt be as attractive as it seems (few short stories focusing on a single senshi).
Im pretty sure if we'd ever see a new material after Crystal ends it would have to be either written by Naoko or created with her official blessings. The remaining unadapted material just isnt strong enough to make the franchise feel fresh or new