I agree that the Air is intended to be a secondary Mac. That’s exactly why I ordered one.
My 17-inch MacBook Pro’s roll is “portable workhorse”, a machine I could use for everything I use my Mac Pro for, if need be. It’s meant to be a “backup” machine with a minimum of tradeoffs. But it’s not a machine that I’d take along on a whim, just to have a Mac with me. That’s the Air’s job. And I got the 11-inch one for maximum portability (and to save a couple of Euros).
The 11-inch MacBook Air is what I’d like the iPad to be, but what it might never become: An ultra-portable yet full-featured Mac.