I don't think this is just a reflection on Xbox. Imo people are just fed-up of digital showcases that hide everything and show nothing.
Not having a dig at Sony or Microsoft, but most of their non-e3 'e3' shows have been abysmal compared to the showcases in real life. The digital format sucks and is a compilation of poorly put-together snippets and CGI cut scenes.
Being boo'd on stage, like Microsoft were, sends a bigger message to the company and is disastrous for PR in relation to some mean tweets. Do you think Greenburg would have got away with showing no gameplay after promising gameplay, and then do it again if it was a live show? Would Microsoft get away with the state of Halo if those reveals and announcements were on stage?
YMMV, but for me, I can't even be arsed with the gameshows when I can just watch the 4k trailers without the adverts and bullshit. But, I'm a gaming cynic nowadays and haven't bought a next gen console yet because the industry is no longer worth the investment in time or money.