I think it is actually pretty smart. Getting more media attention and giving them more time. Making the media feel like royalty always gets better press. Less lines, better press, individual attention instead split among all other participates of a trade show. Finally, if you drop a nice bomb like the launch date and price then you cause major hype, that leads into TGS.
So what does Nintendo do at TGS...simple, finally completely outline the Wii24Connect potential, the Virtual Console prices and how it works, and list of all Wii games played to go online in 2007. That would be huge TGS press Conference that will hype all the way into launch date.