Its not really a price cut.  A price cut would be 399 with Kinect.  Instead they are announcing a new SKU that is missing a major component.  There are pros and cons to the new SKU and as others have said it does make sense to just get it out of the way so that they can spend more time at the conference trying to convince you to get a X1 without the whole internet going one direction or another.  Get the news out early then spend time trying to make it seem like a great move on top of what you have to show.

I blame Don. 360's years since 2010 can be all blamed on Don Mattrick. Hes a excellent scapegoat for all our past problems lol

Because Watch Dogs and Wolfenstein might be big sellers, and are coming before E3. So they might as well take out one more PS4 advantage by announcing this sooner rather than later..

this sounds far more likely then ms having bigger things to show at e3.  ..but npd numbers will help us out here.

Icwhatudidthere ;)

As the OP said, it's probably not because they didn't have time to show it at E3. My guess is that they didnt want any bias going into E3. They may have been worried that people would have a certain stigma towards X1 and the games they showed if there was already a preconception that the system was overpriced. But now that no one can really argue about the price anymore, people may be more receptive to what they show at E3.

It has nothing about MS showing more games at E3.

Honestly i think they were not sure how people would take this news. I mean, they are now just weaker PS4 without any differential. Given, they were already being saw as that.

Watch Dogs, Wolfenstein and NPD may have also influenced.

they are dumping kinect to be competitive,best get it out the way than answer questions all E3 about why they are dumping their interface tech for all but teh hardcore

They could not have done this at E3. It would have been painful in a live show. How do you announce, to the cheers of the audience, that you're scuttling what was once the crown jewel of your system? It would be the same as admitting to another mistake, right in front of a live group of gamers who mostly didn't care about Kinect to begin with. You don't do that live, you do that with press releases. Sure, you can spin it if you try really hard but you still have an announcer up there trying to smile through what is bad news to them.

Microsoft is going to want E3 to be as positive as possible. I expect all the iffy stuff to be announced prior to their presentation.

Because it will be a shame to announce they are dropping something at the same place where they mention how great it will work, can you imagine how will they feel when crowd Yeah for this...