It's not what it used to be anymore, not even remotely close, but still, watching live stream reveals are one of the most exciting moments related to gaming - the impatience, the unknown, the surprises, the disappointments, it's just one hell of an emotional rollercoaster, especially compared to nowadays lazy dropping an article/interview or a short teaser/trailer on the web, which are just... soulless.
That being said, I think that E3 and all the other bit annual conventions suffer greatly due to long development time of current-gen titles. Because not only there are less development studios then they were back in the PS360 era to begin with, but on top of that those studios that are still here need a 3, 4, or even 5 years to make a single game, as oppose to the once usual 1-2 years. So there's not really much to be shown on all those big conventions other than previously prepared teasers or trailers, live gameplays (even the fake pre-rendered ones) are almost completely gone, we are lucky if we even get some gameplay trailers during those shows, because most of the time they show up later out of a sudden on the internet.
So yeah, those big gaming conventions suffer from the lack of content, because the content simply isn't ready at the time, but this year will undoubtedly be big thanks to the upcoming consoles, both Sony and MS have to revel thei consoles, talk about them, show their features, capabilities, tech demos, launch titles and what's not, and Nintendo will also have to make an effort unless they wan't to be overshadowed and forgotten by the next generation.