It's a huge departure. It's a big deal. But it's tied to their business model: Apple is a hardware company.
Apple is not looking at the chip for differentiation. It's counting on its hardware and software for that. If anything, it's taking the line of thinking that the chip inside makes little difference to the quality of the computing experience.
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?
They have a great hardware product, but they've been shut off from businesses and consumers who want to run PC programs, and now they have the software that will allow that.