You need to look at the new sonic as a different game.
It's not a new series. It's just the developers flopping about trying to please fans, but they keep thinking they need to doing something completely new when they need to go back to square one.
Personally, I think they should have two lines of games. One for classic sonic, one for modern sonic. Modern Sonic would drop everything and go back to the Sonic Adventure-styled games, perhaps keeping some of the fun stuff we saw in Colors. Classic Sonic staying classical.
Sonic Generations seems like it would be a great path paving title for doing this, considering it is basically doing just that.