Yes. Heres why: Sonic is the only character who's game design is still his own. Where else can you find a game like Sonic?
Tons of mario clones
MegaMan clones
Castlevania clones
But how many Sonic clones? If you want high speed platforming Sonic is still the only place to get it. Thus his value is retained unlike something like all these shooters and open world games which all offer the same experience.