The next Super Smash Bros. for the Wii U and 3DS will not have a Story Mode because of… the Internet. Yeah, apparently Super Smash Bros. creator Masahiro Sakurai said in his bi-weekly column in Weekly Famitsu that story mode and CG cutscenes would be eliminated from the next game because the movie scenes from it were uploaded onto the Internet. Yeah, that's really the reason for it.
"Unfortunately, the movie scenes we worked hard to create were uploaded onto the internet." Sakurai said in his column (as translated by Kotaku). "You can only truly wow a player the first time he sees [a cutscene]. I felt if players saw the cut scenes outside of the game, they would no longer serve as rewards for playing the game, so I've decided against having them."
While CG cutscenes and Story Mode have gone the way of the Dodo, Sakurai has been focusing on new character intro video sequences for the Villager, Mega Man, and the Wii Fit Trainer. Sakurai hopes to make similar videos for all the new characters. Sakurai also promised that the 3DS version of the game would include a feature that will serve as "a separate mode from the standard versus play." He also said that the Wii U and 3DS versions of the game will feature different types of stages and that there will be some character customization in both games.
Still even with all these new features, it seems like bad form to nix a game mode because the cutscenes you created got leaked onto YouTube. This isn't the 80's where Japan was a walled garden that gamers couldn't see into without reading a magazine.