E3 is not the biggest gaming event in the world, it is not even the biggest in the US. It does, however, usually receive the most coverage. E3 is not for gamers, and it is not held by gamers, but it is entirely directed at gamers. It's a massive advertising platform for the companies that support it. E3 costs a lot to put together, but generates a massive return because of how far reaching its audience becomes. This is what this action is fighting. If nobody is watching E3, and nobody is covering E3, it will just be a massive cost to the ESA.
You might fear that you will miss important announcements or news of brand new releases. On an individual scale you would be right. If just a few viewers refuse to watch E3 coverage then only those viewers (and the revenue they might create) is lost - a drop in the ocean. But if the coverage of E3 takes a hit, then the propagation of its advertising will be substantially diminished.
Here's the icing on the cake: game developers and publishers are not blind to the goings on of the gaming community. If The Escapist and enough other gaming news websites declare their intention to blank E3, then big announcements and reveals will be moved from E3 to other events that will have the necessary coverage. As a gamer, you will miss nothing, and you may discover that events such as PAX, the TGC or Gamescom (any of which are much larger than E3 and involve gamers from all walks of life, not just the industry) hold far more of the "spirit of gaming" than you would otherwise give them credit for.