That is the problem. Sonic was not supposed to be a fast roller-coaster like game, it was supposed to be a high quality platformer. The roller coaster stuff was for marketing, because it was generally the fastest moving game of it's time, with how the levels tumbled and all. In reality if we go by foot speed, I think Mario ran faster in Super Mario World really.
They kind of made it like that because current age Sonic Team is clueless. They kind of dug themselves into a hole with how diverse the series is now, with fans all over the place wanting different stuff.
In a way, I feel bad that they have maybe the hardest to please fanbase in the industry, but then I remember they are easily the worst big developers in the world and stop caring.