E3 isn't open to the public. It's a trade show, which means you have to -somehow- be in the industry in order to get tickets.
I went a couple years back, and the whole OMFG I'M AT E3!!!!!!!!!!111 wears off really fast. The main rooms are just booths competing with one another for lights and to see who can deafen their interviewers faster. But that's only on the main floor.
In all of the side panels, where you actually go if you're actually press (I wrote for a mag so me andthe person I was with were actually interviewing developers and stuff) are really quiet, and very one on one, which gives us time to ask questions and really learn about the game, WHILE actually being able to hear.
I think closing it off is, for the companies, a good idea. However, I really liked picking up Game Informer or something after the show was over to read about all the cool stuff. I guess I'd rather read about than go back again...and if I went back again, it would definitely only be for a day, because it truly is exhausting.
On a side note, if Comic-Con decides to do something like this, I will be
REALLY REALLY ANGRY LEAH. I love Comic Con

And didn't get to go this year
