They are showing more than just trailers. They have Battlefield 1, Titanfall 2, and EA Sports games all available to play for the public. The press conference really was just for the world, but the main EA Play event is actually allowing people there to play the games. EA is changing tactics from E3 because E3 has always been a glorified showcase with no substance. EA wants to make it just about games, so they are demoing the games they have available.
There's nothing inherently lacking in substance in E3. That's on the individual companies. EA is bad at it. And they're just as bad at it on their own terms.
Oh, but look, we have DEMO BOOTHS. We're so open to the public, doing this limited local thing with something we could just as easily be doing by releasing actual downloadable demo versions through our own Origin service. The only reason it's "open to the public" is that's the only reason anyone would go there. Gaming media is more interested in E3, where there's actual variety.
And no one wants to go to a convention just to play a bleeping sports game. At that point you might as well buy a ticket to an actual sporting event.