I think a proper presentation on stage would be much better, more people see it, they can reiterate that the Wii U is new and exciting and it helps hype meters. Plus is a new Zelda title is shown, peeps will go crazy. Sure the same will happen from a direct/event but it isn't the same.
I think people underestimate how the main presentations make reveals all the more exciting and cause a bigger ripple. When I'm watching it live with my buddies on Steam and something amazing drops we all go crazy, regardless of who is making it.
The biggest issue I see is the fact that, like they put it, their fans will come and find the news. "..to communicate news directly to its key audiences, including fans.."
That's all well and good but that'll happen anyway, joe blogs won't go out of their way to watch a seperate thing elsewhere. They need to get themselves infront of people who have otherwise shrugged them off.