@ KumaOso (in regard to Mario)
Well with Mario, Galaxy and even Galaxy 2 were daring and original titles. New Super Mario Bros. (the original, and perhaps the Wii one) were at least something fresh. Super Paper Mario was a fresh idea, too. (I will agree that NEW Super Mario Bros. 2 looks redundant; even the name suggest that)
(in regard to Sakurai's originality)
It's not always "style" that needs to be original, but execution, presentation, setting, and direction. Any of you can say what you will about Smash Bros., but it is pretty clear by the "feel" of each smash bros (and Kirby) game which is which. Sakurai finds many ways to make each of his games "unique," whether they are good or just okay.
Stylistically, you look at Mega Man 9 and 10 (although not as much 10), and their style is essentially the same of the first 5 Mega Man games. They were occasionally as "fresh" and "inspired" as the 1st 3, and leaned more towards those games, but sometimes they felt like the 4th and 5th Mega Man games (especially 9).
Then take a look at Resident Evil 5 (and Resident Evil since then), and the series seems to be clinging to Resident Evil 4's everything for dear life. It hasn't changed it, and if it has, it has been for the worse, and to an action game that happens to have creepy looking zombies. Worst of all, it has lost its' soul it had from Resident Evil 4 and before that. Instead of trying to innovate, reinvent, and push forward, the series is trying to stay the same. (although the worst offender of this was Activision with Tony Hawk and Guitar Hero)
You can stay the same for a while by building on success; that's all fine and dandy. But in the end, you gotta "push" franchises ahead and in new directions, otherwise, the games you are making are literally just add-ons. That is the greatest fear of Masahiro Sakurai. A fear I feel may hurt a few big name studios if they aren't careful (Activision again!)
@ SmashChu
The reason for 4 is plain and simple: The beloved NES icon Mega Man, and arguably the most recognizable gaming character ever, Pac-Man (along with Snake and Sonic, who are both major icons of gaming). Plus Smash Bros. needs some more flavors, and the 3rd party ones are the ones that stick out the most. Most of us will stop caring about the roster when it's just another filler Mario character (Toad, Bowser Jr, Waluigi), another dumb space animal, or a gagillionth Pokémon.