Sonic died when Sonic Adventure came out. There hasn't been a decent Sonic game in years. Sonic should've gone the Mega Man route and stayed 2D. Capcom tried a few 3D Mega Man games and decided it wasn't the best idea for the type of game that it was. Then they went back to exclusively 2D Mega Man games except for the RPGs. Sonic could be suffering from the same problem.
I honestly hadn't played a good and fulfilling Sonic game since Sonic and Knuckles. Then in 2001, Sega started the Sonic Advance series on the GBA which was brilliant and really evoked the style and feeling of the Genesis games. I was proud to be a Sonic fan again when these games came out. I think these games worked so well that Sega should just take a step backwards a couple of generations and just release a few games with high-definition, hand-drawn and animated 2D sprites and backgrounds.
The problem with all the post-Sonic Adventure games is that the cameras still suck, most people don't like any of the new characters with each game, and the story lines are very weak. I honestly think Sega should still go back and make a SatAM game but it probably won't happen. I'm just a hardcore SatAM fan at heart who would love to see more Sonic, Sally, Tails, Bunnie, Rotor, and Antoine, damn it!!