You mean _back_ in San Jose.
It's normally in SJ - they've tried moving it a few times now, but it was always worse.
E3 never has an "open" day during the show; E3 is supposed to be only for the industry types, every day. They tried having a TGS-style open day one year ....all the vendors basically packed up the night before. That's not what E3 is for, and US attendees are not like Japanese attendees (cue Wal-mart videos of Black Friday tramplings & fights).
E3 (like CES) is for two things only:
(1) Get store vendors interested in upcoming games. If they're lucky, the publishers will actually get pre-orders. Thus, E3 is about Sales. Although, now that the Wal-Mart buyers don't attend, it's slightly less so. That's why everything is so elaborate - corporate buyers mostly have no clue between games and wafflemakers. It's all just goods to them. So the E3 "circus show" is to get them excited. Plus, they actually bathe and brush their teeth every day.
(2) Get the press talking positively about the games. Unlike the buyers, these guys are sometimes too knowledgable <g> about games. They're the ones the PR/Marketing's artificial smiles (and artificial women) are really meant for.
Developers are not supposed to be there but are tolerated. The "assumption" is that they're demo-ing the games. Developers are really there to scam ideas from other companies, which is why some companies show certain titles behind closed doors or only show videos - they _are_ probably showing more, but only in a meeting room to select individuals.
Then there's the remainders, the non-industry folks who get in (much like the children that get in, even with the rule of No Kids).
Of course, then there's the reality of the show, which is that almost anyone can get in with a few trips to Kinkos if necessary.
Why don't the E3 people enforce the restrictions on who gets in, including who's legitimately a web press person (instead of just a personal website)? Because the E3 folks love high attendance numbers, because it makes good press. And they want to rub the numbers in CES' face.