Because most Nintendo games on the Wii seems to be sequels.
There is Mario Party 8, Wario Ware: Smooth Moves, Battalion Wars 2, Fire Emblem: RD, Zelda:TP, Mario Galaxy, Mario Strikers Charge, Metroid Prime 3 etc. Let's not forget Mario Kart, Animal Crossing, and Smash Bros for next year.
Can we expect at least more than a few entirely brand new games from Nintendo for 2008?