Even back when it was new and I was enamored with his edgy attitude and absurd game-breaking speed, I still got frustrated with how poorly the speed and platforming gelled. I couldn't tell if the game wanted me to go fast and tear through each stage, or slow down and take my time. As the series went on, they started throwing in more "full stops" that required you to carefully navigate the environment. That wasn't fun, at all.
Sonic needs a Dustforce-like makeover, or maybe even something like this:
I've played the hell out of Dustforce and love that game, but you're pratically comparing games from two entirely different genres. Dustforce is a technical platformer. It focuses on air movement and acrobatics, with a smaller emphasis on momentum.
Sonic is a straight up platformer with a twist in that it's a generally more fast paced game than most other platformers. The "roller coaster" parts are just there to spice things up in between platforming segments. Anyone claiming that Sonic is supposed to be all about speed and you're never supposed to stop moving is a dumbass. In the classic games, speed was your reward for memorizing the terrain. As you got better at the game, you got better at flawlessly traversing through platforming segments without breaking the flow. THAT is your gel between speed and platforming.
But if that really doesn't satisfy you, Boost meter. It's not in this game, but it's exactly like the Dustforce combo mechanic except it rewards you more frequently.