I think that E3 will be important but much more for Sony and Microsoft.
Nintendo
Ask your mom what she thought about last years E3, better yet ask the people in the retirement homes, or even your girlfriend who loves your Wii lol. I bet they will all ask you "what is E3"? Most of the casual gamers don't even know what E3 is enough to care about it. Though if Nintendo wants to grab some more "Hardcore gamers" then they still need a good show but they don't have to be the best because most of there money is coming from the "non-gamer gamers".
Microsoft and Sony
Microsoft and Sony are going after the more devoted gaming crowd, those people will be concerned about E3. And for that reason alone they both need to leave Nintendo in the dust with their shows.
Sony
Sony needs games, games, and more games. Nothing more, nothing less. Also they need a very good showing of their exclusives.
Microsoft
Get rid of those damn online fees(won't happen) and have Halo playable.
