It makes some sense. For practical purposes you really probably shouldn't launch Zelda, Mario, Red Steel, two Square Enix titles, SSB, AND MP3 all on the same day.
Plus they've made a semi-big-deal out of not having the patented Nintendo long-assed drought after launch. Spreading out the releases a bit so as not to allow some interesting games to get sort of written off as an afterthought isn't that bad a thing. It seems like there are enough games in the pipeline here to get off your 20 launch titles with 5 or 6 big names and still have at least one major release every month up to the next E3.
Assuming we get a November launch, we could see
Launch: Mario, Zelda, Disaster, Pilotwings, Wii Sports, Two SE titles, Red steel, a dozen or so other titles
December: SSB
January: Resident Evil: Whatever Edition, Wario Ware
February: MP3
March: New Sonic Title, Fire Emblem
April: Namco RPG, Excite Truck
May: E3 2007