To begin with, Sonics early 2D years is heavily stylized in a cartoon fashion, relying heavily on pixel aesthetics within the art to express and develop immersion without jarring visual cues and design. Within any progression to 3d, the half cartoon half anthropomorphic realism is greatly handicapped due to the nature of the clash between more sensible aesthetics and connotations of representation with realism, especially with gameplay in mind (a clear example being Mario 64 where Mario's feet or hands enlarge during kicks and punches to accentuate the kinetic impact and hitbox). Sonic team however had a unique and interesting method of developing Sonic into the 3d port where transitioning the initial "chibi-classic" sonic may have been not only difficult but taxing on the systems of the time (the Dreamcast), age. During development Sonic had been around for almost 6 years and they capitalized on this by entirely altering his looks, his limbs and torso growing longer while the head became less circular. A bold move no doubt but...how would this fair with the already established fanbase?