My guess is that Microsoft was going for more of the general audience who bought tons of Wiis with this announcement. They’ll get more focused mainstream media attention from this event, since E3 will be full of info from tons of different sources. The general public will be more intrigued with using Kinect 2.0 and the TV integration. At E3, they’ll blow their load on games and more gamer-centric ideas. They know that we’ll be watching both, whereas more of the general public will only pay attention to today’s reveal.
I’m going to withhold final judgement until after E3 but I’m hoping they really impress then, because as of now, I’m leaning towards PS4 (especially with paying a FULLRETAILFEE to play rented/borrowed/used games).