You got e3 wrong.
e3 is not about attendance, because it's not a public event. It's an industry conference. No matter how much we can argue about e3 importance, at the moment, it's still the biggest gaming event in terms of broadcasting audience and industry relevance.
Yeah if you take the attendance away you have that broadcasting audience left that can just easily watch the same information on a Playstation experience or a Nintendo direct,that sort of negates the relevance of E3.
Even so, it's still the biggest show out there.
Besides, it's not because you can get news by reading a blog or watching a youtube video that you can just get rid of theatre presentation and an industry conference spot where all parties are present, competing there to make the biggest show.
It's the same about those directs. Directs can get communication across as just as theatre conferences, but that doesn't mean that directs are better or worse than live theatre conferences. We can have both and in the end directs are just cheaper material, not exactly more interesting.
Youtube sure can host a bunch of trailers in a playlist so that everyone can watch them while sipping expensive Starbucks rubbish, but this is not the same experience of having a single weekend in the year of live news and presentations from a live spectacle from a real theatre and conference building where the real VIPs from all the industry parties are there working together sweating to present to the world their biggest products.
Can we get rid of e3? yes. Can Nintendo, Sony and Microsoft get out of it and each of them just make their own event, on their own dates, following their own rules, protecting themselves against competition and spending the lowest million possible? yes. But that's just boring.