The problem with Directs is that they only hit the most enthusiast of Nintendo's fanbase, while missing any consumers that actually need to be marketed towards. Do they're pretty useless for getting out new info to the average consumer.
To me, the Iwata Asks are the real treasure. Nintendo Directs are just a way to disseminate news about what's to come on Nintendo consoles, and as such, I think the gaming media would be a better way to get that information out there to the "general gamer" (and also I think there should be huge banners that advertise new and upcoming games to WiiU owners the same way I would see Gears of War: Judgment guy after turning on my 360 last Spring
(BUT DON'T GO OVERBOARD AND SELL AD SPACE!)
^I suppose my views of Nintendo Directs vs. Gaming Media have been short lived. I only started watching them since last year so I don't remember how they were during the Wii heyday when there was lots more releasing on Nintendo consoles. So my impressions may be incorrect, only based on a short part of Nintendo Direct's history.