I feel like Sony skips E3 a lot? And just does their own show.
They dumped PSX for the same reasons. Too expensive, too little return on investment, too much impact to dev teams, the existence of better, more immediate methods of delivery of news/content.
E3 is a zombie at this point.
Actually zombie isn't even right, it's terminal. E3 is going to die, it is just a matter of when, not if.