I don't know that your first point is necessarily the case, though. I would argue that Metro works well on both small screen touch interfaces and larger screen point and click interfaces. The Metro buttons or boxes or whatever are actually very click friendly, and I think keyboard/touchpad/camera/mouse gestures will make it extremely usable. I might go as far to say that the Metro interface seems to transcend interaction type.

I do understand the 2 OS's concern. I do imagine that after a few years and maybe another iteration or two, people will move on from the need for the traditional windows desktop experience and appreciate the same look and feel across phone, tablet, laptop, and desktop. People will be initially frustrated, but even Facebook can't roll out a minor redesign without millions of people freaking out like FB stabbed them in the back.