>1. The Windows app store is Metro only
Well, the app store can link to desktop apps.
The reason is the same that the OS X app store is heavily sandboxed. Microsoft does not want to distribute via its store BonziBuddy type borderline adware/spyware/bloatware/toolbars with always running processes and services and icons in the system tray. It's a pain to enforce on Desktop apps. Contrast that with WinRT apps which are totally self contained and sandboxed except for integrating via Charms.
>2. Developers as well as normal users are actively looking for ways to avoid having to interact with Metro.
That may be true to some extent, but developers seem to be catching on. Jeff Atwood is upbeat: http://www.codinghorror.com/blog/2012/07/betting-the-company...
Two thousand apps without even the OS really launching or the Surface being released is nothing to sneeze at.
I think the real differentiator will be how well the Windows RT and Windows 8 touch enabled laptops will sell over the holidays. If they sell well, developers and apps won't be far behind.