MudkipYeah!
Vastly Short Attention Span
Eh, I wouldn't just say that the solution is to bring a whole new team into the mix, as evidenced by, well, Big Red Button pretty much. The bigger issue is Sega is really trying to appeal to way too many crowds at once. And as we all know, there is no pleasing everybody. Instead of focusing efforts on quality, they have too much focus on the nostalgia card and "all the cool kids play it". Things like that. Sega want more people in the franchise, while also keeping the oldies in. It really went downhill all the way back at the start of the "dark age", I'd say with Sonic Heroes. They kept changing the formula up so much that it more or less alienated old fans from Sonic games. Sonic Team just didn't establish a constant formula that could be changed just enough to keep things fresh, yet not to the point where old players feel that it's an entirely different franchise. But that's just my take on this.