Huh? So if I understand you correctly, apps shouldn't be allowed to be cross device?
Clearly that's not
what I said. My point was that applications should be built for the platform they are running on and having an app that runs on desktop, tablet and phone can and does lead to compromises being made.
And what the heck is a "tablet app"? If you're referring to Metro apps, they are not "tablet apps". That **** has been debunked to death. I've been running Metro apps on my desktop without issue, in fact some have even replaced their desktop equivalents. Skype, Calendar, OneNote, EverNote, SkyDrive, Bing, Weather, Lync, Yellow Pages, Kindle, Wikipedia, etc. I could go on, but I won't. I run those AND more on my desktop. They work, and they work well.
By "tablet app" I don't mean all Metro apps, only those that are clearly not designed for desktop use. That includes Mail, Music, Video, Skype, Camera and Calendar - they all function on the desktop but are inferior to their desktop counterparts. There are plenty of Metro apps that are
suited to the desktop environment, like XE.com, Cocktail Flow and Solitaire - they're still limited by the WinRT platform (can't resize them; rely on the Charm bar; right-click menus that appear away from the mouse) but they work well on the desktop. Some of the Metro apps you list are terrible on the desktop, like Skype, SkyDrive, Weather, Calendar, etc. I can't see why anyone in their right mind would choose to use the Metro version of Skype on a desktop system.
The limitations are all the more apparent to me because I have a 30" 2560x1600 display and heavily multi-task. The Metro versions of Chrome are simply unusable for me because they are terrible for any website that has a flexible layout (Blue's News and the Neowin forums are a good example of that), as it's very difficult to read text across the full width of the screen. Using a Metro app prevents me from doing other things, so they are only good to me for specifics purposes (playing Solitaire is one example).