E3 isn't for gamers, or general consumers? It's like the Cannes film festival. It's an Electronic and Entertainment Expo. It's where people in the industry get together to see who is selling what and make deals. It used to be the place where stores like Walmart, GAME, GameStop, etc. would decide how many units of certain products they are going to order for their stores. It's also where developers, studios, publishers etc. meet up in back rooms to discuss deals. Again, not for the average joe/jane gamer.
But like Cannes, Fashion Weeks, and other trade shows journalists go along to get an early scoop on what the industry has got in store. The presentations were for buyers to get them pumped about a product and order more units. But because journalists reported it to the general consumer, and created a marketing opportunity, the whole thing has been skewed towards the general public. It's now a bastardised event. The deals are still made, the store buyers are still there, but a large proportion is media baiting.
It is what it is, if people lost interest there'd still be an E3 trade show for people to do business, just not as grandiose.