I wouldn't go that far, PP7's story is bad, but I while I might personally have issues with the later stories and find the setup with the same 5 characters every time to be repetitive and stale, they are serviceable and have some true strong points, like the Tetris characters or Rafisol, along with their own respective arcs. Special mention goes to the latter, since I wasn't that big on the idea of an anti-Ally character and thus didn't expect to like her, yet she quickly became one of my favorite post-Fever characters, even rivaling T and X, simply because they made her a very compelling and in my opinion, underrated character.
My point is, I'm sure they could do it better, PP7 really isn't indicative of the writing quality of SEGA's Puyo output.
Sorry, maybe I didn't make myself too clear in my last post. When I said that I was a bit turned off by SEGA taking another crack at a dark Puyo game, I didn't mean that PP7 COMPLETELY turned me off from the idea or that SEGA shouldn't take another crack at it. It's just that SEGA REALLY needs to do a bit more research on dark stories (or at the very least, look back at what Yo~n did, and expand/improve on it.)
I'm the complete opposite, I'd hate it if that were the case, because the Fever games were a lot more about Primp at large (with three focus characters of course, but still) and everyone around it, rather then a single main character. Glorifying Amitie like that goes against all of that.
I honestly just don't see why she always needs to be a main character, especially when characters like Raffine or Sig, who have much more to work with, are constantly treated as expendable. I mean Arle wasn't a important character in the Fever duology, since there simply wasn't a place for her to get a bigger role, but did that hurt the narrative? Not at all.
You know what? I'm sure I've said it before, but looking at it now, the fact that SEGA didn't give us enough games during the Fever-era to really delve into what Primp has going on behind-the-scenes really bothers the ever-loving out of me.
Also, I guess with Amitie being referred as this in PP7, it just rubbed me the wrong way even more than if she was referred to as this in the Fever duology, considering how she had practically no reason to be a (major) element in that game's story other than the 'A' Trio concept (Although, I GUESS the same could be said for Arle, too?).
BTW, I'm certainly not saying Amitie HAS to be a "front-and-center" type of main character. Heck, as you've said already, Arle's proven that that's the case not being the main protag of the Fever duology, and Ringo could easily do the same thing (As in, not be a main character for a game and nothing would be taken away).
Basically, with Puyo Puyo's VERY extensive cast, the 'A' Trio could be replaced by the 'S' Trio, or even the 'R' Trio as the main protags of a game, and nothing of consequence would occur.