One thing that I think often gets overlooked in discussion of Colors is that it was never meant to be the second coming of Sonic games, and a lot of the complaints about it (like stale level design in spots) can be summed up by Sega just not thinking it was that big of a deal. It was a dinky little Wii spin-off in the vein of the storybook titles (its status as a "mainline entry" seems to be retroactive), that ended up resonating extremely well with the fanbase because it was the first time Sonic Team actually tried making a modern Sonic game without either overloading it with terrible alternative playstyles or featuring a poorly-executed, melodramatic story (or usually both). "It's like an episode of Adventures of Sonic the Hedgehog" was a selling point in fan circles back then, with 06 still fresh on everyone's minds. This game came out around the same time as Sonic 4, which is what Sega was really pushing as the game "for the fans." I remember there being a convention where both games were featured, and they were interviewing a Sega rep who only wanted to talk about Sonic 4, and kept acting surprised every time the interviewer pivoted to asking about Colors, and even openly wondered why they were so interested. Colors actually looked fresh and exciting by comparison, whereas all the gameplay footage of Sonic 4 at the time could be most charitably described as Worse Green Hill Zone. I imagine the team behind Colors felt considerably less pressure to revitalize the franchise in the same way that basically every game in the series is hyped up as the glorious return of good Sonic games, and it probably goes a long way towards explaining why it's one of the better entries in the series. More relaxed environment = better for creativity and polish, and lower expectations from the fans. Kind of funny how you almost had the same dynamic in reverse with Forces and Mania - Sega pushed "Project Sonic" hard at first, and it ended up being a total dud compared to the humble little fan game-with-a-budget Mania being hailed by the first great game in the series, without any qualifiers, arguably since the Genesis.