Why should he, when he knows Win7. It's called Windows 8, not Metro 8.
But it has been described as a "re-imagining of Windows". So anyone who's paid even the slightest bit of attention would expect it to be different.
When Ubuntu switched from the old Gnome desktop to using the Unity shell by default, I was completely lost the first time I used it. It took a lot of googling for ways to do things before I could use that. And I'd used previous versions, so according to you they're not allowed to introduce major changes like that. Better go to the Ubuntu forums and write lengthy complaints about that!