In regards to Forces' storyline, I think it worked fine as it does two key things. It makes the focus of the game stay on Sonic v. Eggman, which a Sonic game absolutely needs to be, and established that Eggman is a credible threat as opposed to the blundering buffoon he's been in so many times in the past.
That's already happened before in 3 times in a row, Colours, Generations and with Lost World tricking players into thinking it was more into the plot but secretely just Sonic vs. Eggman in the end.
Now I don't mind it in the slightest if it was given at face value as I can enjoy an old fashion Sonic fighting with Eggman but the problem was the effort and promotion material that went into it felt like short change for something bigger, if they cut then storyline hype and character dynamics then I would be fine.
Also I don't think there's a problem with going off the beaten path, Sonic can do more than just fight Eggman over and over. Mario has been trying multiple angles of saving Peach (or Sprixies in 3D World), why can't Sonic do the same when trying to save the world.
EDIT: Also a massive problem with this is that Eggman didn't look like a threat at all, Infinite and his allies did all the heavy lifting (hell Tails who was afraid of Chaos at the beginning just laughed at Eggman) and even when they were gone the attention was more on the Phantom Ruby than Eggman himself with Sonic still not taking him seriously.
Giving more backstory to Infinite and the Avatar would have made the game not be a Sonic game and instead be a "Sonic Friends" game, which would have been much a weaker premise. Infinite's abilities are meant to be his key trait so keeping his backstory light works, as does his only considering the Avatar to be little more than some scared kid that keeps blundering into his way. Having them both play pivotal but not central roles actually made them both feel a bit more meaningful to me, since they weren't being overused or eclipsing the the series' two main characters.
I feel like it is possible to give these 2 characters more meaning without taking away Sonics spotlight, Adventure 1 did this perfectly. Not that I have problem with shared spotlight but it makes the Avatar feel kind redundant to be inserted the story in places.
I also heavily disagree with it making a weaker premise, I think seeing multiple characters being affected by this battle would've strengthen the premise.
Now I'm not saying Infinite and the Avatar should take leading roles with Infinite betraying Eggman as that would make Sonic and Eggman be more redundant but just give more reasons to care for Infinite instead of him being mocked for being overly edgy over nothing.
If they really want to expand on the story and give more time to certain characters, doing it in the form of standalone episodes like Mission Shadow seems to be the most logical choice. It would also give them more freedom to tailor the whole experience for that particular side story, rather than bouncing around between too many characters at once in the main game and diluting their impact.
I can see this but the problem is that Episode Shadow was able to do this more easily since it was a prequel doing it within similar timelines just create Sonic 06 levels of confusion of when things take place.
As far as the stages go: While I certainly want more of them, especially ones that make use of Infinite's abilities (stage 16 is by far my favorite for the gravity/perspective shifting gimmick), I don't reaaally think they need to be that much longer.
If they had more to make up for a lack of length I probably wouldn't mind it either to be honest.
Plus, and this is something a lot of people overlook, it makes the game more accessible to younger players, who are the age group Sonic games are targeted to.
This is where we get to the confusion of the franchise and who it is made for, mainly because Sonic has an identity crisis. Previous game Lost World, as well as Colours were targeted towards Mario fans. Generation was targeted towards the fans of all ages themselves. It's impossible to really say what the games are designed before especially with SEGA's new approach of embracing the internet culture of Sonic, it could be them targeting towards deviant art.
Long story short, we shouldn't assume it's targeted towards younger audiences because its age rating and presentation.
Plus, I really can't help but feel that trying to properly make a Casino Night tribute stage work properly with modern Sonic would just end very poorly.
I always found Casino stages in general to be 🤬 regardless. Even still, Lost World shown to be decent in comparison to the hell of Bingo Highway from Sonic Heroes.
