I almost wonder if they don't want to add KSS to MM at all. The last time they did was with Mei-chan and that was already six years ago now.
I liked Itsuki so I'm glad she debuted but I do wish it had been somewhere else. I've been tired of the single member additions for awhile so I'd liked that Tsubaki was getting large groups of new members, and only every few years. And even if there is a grad upcoming they were still relatively one of the largest groups right now with Anju, Biyo and ON all dipping below 10 members (and MM potentially about to as well).