So they truly have no idea how to make Sonic anymore.
Going by this
https://www.polygon.com/2017/9/19/16333174/sonic-adventure-3-will-never-happen
Iizuka on Polygon said:It's not that Iizuka isn't on the same page, he said. It's just that Sonic Team isn't interested in repeating itself.
From the developer standpoint, every Sonic game that we're making is taking new steps and advances, furthering the game in a new direction, and that's dictated where the Sonic series has been going, Iizuka said.
Instead, we're likely to see more Sonic games that try new things in much subtler ways.
it seems Sonic Team lack the passion or interest to even try.