I always said Sonic X-treme sucked, now here is the evidence.
/joking
Really sucks hearing the bad reception. It seems Sonicteam may have been playing it safe with previous games for a good reason. They'll never learn
What won't they learn? How to implement drastic changes to gameplay?
Personally I think they do, at least the current team. But their problem is they take time to develop the idea. It took them three (Or two if you think Colours is better) to get the boosting gameplay to acceptable standards and I feel the same issue prevails here. The system itself seems fine but the level design is lacking and for a group not known to hit the ground running, trying to put in a complex level design was always going to be a big task.
It was the same for say Naughty Dog, compare Uncharted which is very lackluster, to Uncharted 2*
*Note I am not saying Sonic Team is anywhere in terms of quality to Naughty Dog, just some developers take time to grasp new ideas.