We're finally getting to the interesting bit of this (off topic) discussion: the perception vs. reality of speed in Sonic games. Sega likes to tout Sonic as being ultra fast and this is depicted in a lot of Sonic related media, especially the TV shows. However in the games, perhaps due to technical limitations, Sonic isn't actually that fast. He is still fast, but only as fast as an Italian plumber when running. The human mind may play some tricks on us when we remember the good old times as well, which is why to most people Sonic always felt fast when in fact he wasn't fast.
If you played the first Sonic game today you'd see just how slow Sonic actually is vs. current games. But just like the speedrun video above demonstrates, even in an excellent game like Sonic Generations, there's the difficulty of controlling Sonic from getting out of bounds. When we get to very fast gameplay, developers have an insane challenge making sure things stay put and don't clip out. It's why none of the recent Sonic games have been that fast (e.g. Sonic Lost World, Sonic Boom), because it's a very ambitious goal to meet the fans' expectations. That's why we'll be stuck with a slow Sonic for the most part.