Once again, lemme pull my GAF post:
Says who?! Remember, the early Sonic games gave you bonuses for beating stages in under 30 seconds! They don't have to be 5 minute epics, in fact, the levels are worse that way! Yes, Sonic games are brief, but it was their replay value that made them what they were! You actually WANTED to go back to Green Hill Zone and try to beat your old time by exploring for new routes.
I would have also accepted the answer, "Well, another key aspect to the old Sonic games was tried-and-true platforming, see Marble Zone, Chemical Plant Zone, Carnival Night Zone, and Quartz Quadrant Zone."
Look back at the Genesis games; the stages were only long if you lacked moderate skill. There were 2 or 3 routes through the same distance, and I'm hoping that's something that has been done in Unleashed.
There is no reason, no need, for the Werehog. Not even for the sake of platforming, which has been handled very well by the player provided there was plenty of visibility and the Gimmicks weren't vague (Sonic Rush, Sonic Heroes, I'm looking you square in the face).
I understand that creating long stages in 3D isn't financially responsible. Time to go to 2D.
Also, play the Genesis games, and you'll notice something:
There's no way Sonic is maintaining the insane amounts of speed that he's doing in Unleashed.
The Genesis games are snail's pace compared to this game, and I think if the level maps were put side-by-side, it'd definitely show. Which is better? I'd say Genesis, considering that it also allowed careful manipulation of Sonic's jumps for tricky platforming.
And now, let me add to it:
Remember how Sonic CD unlocked secrets by the Time Attack? Remove Ranks, make the goals a little more manageable so that the majority of people could have these bonuses, and ta-da.