I wouldn't blame Iizuka for the different inconsistent worlds problem that the series has. I mean, look back when he directed during the 1999-2005 era of Sonic. Say what you will about the quality of those stories during that time, but at least it was consistent. Each game felt like it was in the same world as all the others. The mythos that was built up all made sense together. Little things here and there from previous games would be referenced and expanded upon....in either big or small ways. It felt right.
Now look at the 2006-2010 era of Sonic. It's all over the freakin' place. Final-Fantasy-princesses, genies, time travel, getting sucked into storybooks, evil alternate dimension twins, alien birds that race hoverboards, running through donuts, werewolves, Pixar looking people, fighting King Arthur, robot pirates, like holy crap WHAT IS GOING ON?
1999-2005 era of Sonic at least had rules, man.
I'm REALLY tired, so this block of text probably made no sense.