It seems obvious to everyone but you that spindashing and rolling in 3-D space doesn't fucking work!
When he is boosting, make him roll instead of just having a blur effect come out of him. Simple fix. It would make more sense, not just because that is how he used to gain speed, but because he smashes into things when doing this. He has to protect that face of his!
Games like Metroid Prime, Super Monkey Ball, Kameo and tons of others (including download-only releases) can have normal rolling physics perfectly fine, I do not know why Sonic Team is incapable of this. I assume they do not try because they do not like him rolling, or simply do not know this is what made the character unique to begin with.
Have you played Sonic Adventure or any of the 3-D Sonic games that let you roll? It's useless and pointless in 3-D. You just end up veering out of control. They took it out because it became obvious is just wasn't working.
Spindashing worked fine in Sonic Adventure 2. I can understand it was kind of glitchy in Sonic Adventure 1, but much of that game was designed with the Saturn in mind, which did 3D spaces differently, and it was slower originally too. Not the perfect indication of something working in 3D or not.
If veering out of control is the problem, then the games are too fast. They need to focus on it being a platformer instead of a racing game.
Spindashing in 3-D space makes less sense than homing attack does in 2-D space. (Not that I'm big on either.)
They never attempted it in many ways, but always tried similar concepts that were not working or just replaced them with stuff like the sliding. In the case of that, I do not know why he is sliding on his back, it could just be the same thing with a spinning animation.
Still, Sonic Colors is over half 2D anyways, I do not see the problem if not just for these sections.