Well, it wasn't so much the characters as the story... *I believe the Japanese version of the game had 4th Hokage as a playable character, so to see that they took him out of the US version was disappointing. *However playing through the Heroes mode was boring because it was nothing more than a glorified arcade mode - there weren't any cutscenes and there was no overall story progression.
i don't know because in newer games there is * lot of character but you can finish story mode in about 3hr so i would prefer if they concentrated on making story longer instead of adding lots and lots characters.
They need to have a more focused story with more moves and better characters otherwise it was a great game with pretty good graphics. also they should let you skip the special move cutscenes