Are you sure that's the nature of Win 8, or just the Metro interface?
It makes seven kinds of sense to me to have two different interaction modes for such a device.
Win8 has 2 modes, Metro (now renamed to something I can't recall) and Desktop. Metro is equivalent to the Start button. If you launch a Metro-app, you'll stay in Metro presentation mode. if you launch a legacy app, it'll flip to desktop mode.
Desktop mode looks like normal Win7. For the record, Win8 is based on Win7. Only Metro-mode changes the API stack. When you flip to Desktop mode, you are basically running Win7. They just turn some stuff off to slip you back to Metro as fast as they can.
Like iOS or Android, Metro is made for doing one thing at a time, with some basic task swapping available. Good enough for somebody googling while watching TV. Not good enough for somebody trying to run Visual Studio to write a program, with SQL Server Management Studio open to manipulate the database and IE open with 10 tabs open to research a problem with something plus Outlook, an IM client, and Explorer to look at the file system you are manipulating with your code.
In other news, my buddy just bought a Google Nexus 7 for $250 w/16GB. He likes it. He is an iPhone user normally. The price was the factor for him. He figured he could live without being able to share apps across devices (its not like they're expensive).
He did not cite any reason that struck me as "only Android" could do that, as compared to iOS. Which is something to remember when we get into nerdy debates about the merits of each OS. Most normal people aren't interested or are less impacted by the details that we think are important, like storage expansion slots (the Nexus7 has none, btw). the app stores are over flowing with stuff, the probability of their NOT being an app a normal person needs is low. There's knitting apps for Pete's sake.
I suspect normal people care about:
is it easy to figure out?
is it durable?
Does it do what I think I want to do (which it turns out is pretty basic and less than what nerds expect)?
Does it look good?
Is there a cheaper model?