Games have been allowing players to choose among directX versions for a long time, is there something radically different about DX12 that would change that?
In mine and others' experience, DX12 significantly improves eye candy without needing significantly better hardware. This is also meant to be a playable DX12 tech demo, AFAIK. Plus, the Xbone game already runs on DX12, so there would have to be significant changes to the engine to support DX11, which would just cause problems, since we all know how bad MS usually is at PC ports.