I don't see what is the big deal. May be I'm just very jaded, but I can't remember a single E3 conference during the last couple of years that would have left a lasting impression on me. May be all those leaks are to blame, but I haven't seen a (positive) surprise announcement with WOW factor coming out of an E3 conference (by any of the big three) over the last three or so years.
Seconded and as an additive the fact that developers from the east kept saving up their salvo for TGS effectively divided the relevance of both shows.
Then there was the fact that everybody had to have their own shindig regardless as to how bizarrely named they might be (SE I'm looking at you).