Do you realize how hard it would be to make it recognizable? It's no big deal to make a blue man, painting a cat-looking face on him, and giving him gloves and shoes. But that's not wont make it any easier to recognize him. It's his long pointy hair that gives us the instant impression that it's Sonic. As skins are bound to be in squares it'll be hard, not to say impossible to make a proper skin.