Better late than never.
But we were told that the Kinect 2 cost nearly as much as the XBO to produce. If that's the case then just dropping $100 leaves a lot of meat on the XBO bones and stopping at $400 to match the PS4 doesn't accomplish much when the PS4 is known to be 50% more powerful a machine.
At least with the Kinect 2, Microsoft was able to make the argument of added value. I'm happy they finally dropped the mandatory peripheral shenanigans but matching the price just makes them the ugly twin.
However, they do stand to make a lot more profit instantly at the price for every unit sold. If that's the goal then I wonder how much faith they place in the future of the product. I guess it just makes more financial sense to stagger the price drops though. So they get two rushes on the console instead of one.