Apple will keep doing what it's doing, and most likely that means they hope Windows users will make the switch on their own. But they're not going to tear down what they've built to try to conquer the OS world.
Apple is a hardware company - they build software to sell the hardware. The question really is, Why not support the installation of Windows on their computers?
When operating systems began integrating features that were in other systems, they were well on the road to becoming undifferentiated from each other. With widgets, they see an opportunity to win users by being unique in how free content is pulled into the system.