Every fan has their own ideal Sonic. Every fan will [sonic slicer] at their perceived inconsistencies. Hell, I do it too, just get me talking about Tails. When Sega offers a lazy/rushed development, that's one thing, but you can't really fault them for not measuring up to a million different expectations at the same time.
Again, though, who's at fault for that?
Sega were the ones who allowed Sonic to be marketed in so many different ways since his introduction in the 90s, and when he quickly became their licensing [sonic slicer]. There were the games. There were the cartoons. There were the comics. And several different permutations existed for of all the former things, depending on the region of the world you lived in. This would only go on to be compounded, thanks to the "Adventure-era" Sonic that a new generation of fans would grow up with. And all of that was fine, as long as Sega was making money.
But, fast forward. Now we're in a world where Sega is floundering about with their "golden boy", simply because they really have no idea of what to do with him. That's why the tagline "returning Sonic to his ROOTS~" is meaningless; how do you return something to its grassroots condition, when pretty much everybody was allowed to grow up with the character/concept/world in their own way? Even worse, when you have people like Iizuka, who don't exactly paint themselves as the sharpest crayons in the box either?
You know it's dysfunctional when there are still arguments about the "proper name" of Sonic's main antagonist. On the other hand, when was the last time any significant argument about the name of the Princess of the Mushroom Kingdom took place?
So, again, Sega has no one to blame but themselves for the mess they have now. Mario, and especially Mickey Mouse, existed as ideal models of how to market a world-wide character and brand, in what could be described as a uniform way. That's definitely not what could be described for Sonic...