"One thing that a lot of people were worried about with the Wii was that since Nintendo was talking so much about changing gaming and targeting non-gamers that the "traditional" type of games would disappear. "
Yes, I wonder
who that was...
Super Smash Bros. Brawl is a really important game for a number of reasons. It won't just be a huge seller; I mean, seriously,
Smash Bros.? Yeesh. Aside from this, it's a graphically beautiful title (on any system), and it a demonstration that Nintendo isn't about justifying the Wiimote at the expense of a game's quality. Smash Bros. is probably most responsive with a traditional gamepad, and as such, that seems to be the default method.
Also, I think it's a good thing that it's not a launch title. The Wii's launch will be successful regardless of whether Smash Bros. is part of the line-up or not. Twilight Princess, Dragon Quest (in Japan), and maybe even MP3 will sell massively with the console, so it doesn't need SSB. However, as a shining beacon of light in the post-launch period, it can do a whole lot more to flesh out the Wii as a successful platform. As Harrison (I think it was him) said, it's that six months to a year that really sets the console's future in stone, and Brawl would definitely be a "rock-solid" game, if you catch my drift.