>>64136893
Because the focus shifted.
Back then, the "gacha" was practically free, but characters were also just talking PNGs. You could pump out a bunch of them, select a few popular ones, strap them together as a team, then write a compelling story. It was more about writing a story then selling a character.
Now it's not. Gacha is not free, but the characters are fully voiced coupled with 3D degeneracy. Costs a fortune to make, but also pull. So each banner gets like 1~2 new characters. On top of this financial gambit, they have to take GFL1 into consideration because it has not ended yet.
What they end up with is extremely limited writing capacity because they have to stall the main story to not spoil and wait for the production of more story-relevant characters, but at the same time sell the gacha banners because the production value went up so much.