I'm not stopping you. I'm just saying you are. ;)
Sadly, I cannot relate to your issues ATM - maybe I would have back in the middle of 2010s. :-)
For so long I've wanted Kajiura to stop working with Koiwa on mixing, I've wanted her to stop working with Chinone on mastering (granted, that's on Sony not YK), I've wanted her to stop working with FBM so much so she could get her own keyboard-and-synth-fu juices flowing.
I personally do not need Keiko at all. Heck, I think I'll survive if YK stops working with Yuriko and I am a Yuriko stan - YK would find someone to fill that gap or would have to get creative - whether I'd like it as much as having Yuriko I do not know! We had Kaori Nishina back in the day next to Yuriko; I guess we now have Joelle alongside Yuriko, considering she's doing both BGM and sometimes backing vocals on songs - nocturne, English Fena songs... Heck, I'm sure both you and I would be thrilled if Kajiura started releasing music with her own vocals.
I'm also sure not everything is up to her. Even the amount of work she does. Delays or cancellations are not her fault. Maybe Kajiura isn't actually welcome in the anime space now? Maybe they can't afford her? If there's noone on a project production team to actually want Kajiura then what is she to do? Change her own standards? Completely change her sound?
We went through so many metas. "Kajiura peaked in 2000s"; "Kajiura peaked with Kalafina"; you're proposing "Kajiura is in her prime now but not taking advantage of it".
Back in the Alicization thread I remember saying that it managed to revitalize me for another 10 years of MEH projects. Happily, it's been going slowly but steadily since then. At least for me. I'm sorry you did not like Fena. I'm sorry you did not like Vanitas. I'm sorry you did not like Kaze yo Arashi yo. I'm sorry you did not like ANTI-HERO (though I seem to remember you liking it). I'm sorry y'all don't like (m)any of the new Aimer, LiSA, JUNNA, whatever singer or FJ songs.
Not everything hits as hard as I would like but I happen to like a lot of her output even now. It is amazing to me that after 20+ years, even with bumps along the road, I still get projects (or significant parts of projects) of hers that I enjoy.
I hope that Kajiura does something you like again, too.
Happy New Year!
Love,
grunty