Btw Bowser and DK aren't on the "Box" either... Same with Snake and Zelda, and Diddy Kong...
You see where I'm going with this.
DK, Bowser, Snake, Zelda, or Diddy Kong aren't big enough characters that would sell more of the game if they were on the box. If Sonic is in the game, not putting him on the box would be a huge mistake, just because so many people will randomly see the box and say "ooohhh Sonic is in it? I'll buy it."
I thought the same thing about Sonic & Mario olympics, and I'm doing my best to ignore that game, but I'm hoping we can count on Saukrai to include the #1 most demanded character in his fan polls. I'll be really upset if we get characters like Geno or Ridley and not Sonic.