Physical keyboards are sooo 2009
Lukas Mathis speculates in Virtual Keyboards, Real Keyboards the reason for the iPhone's virtual keyboard:
…I would assume that the reason why Apple went with an on-screen keyboard is not that they thought it afforded a better typing experience than a physical keyboard. They went with the on-screen keyboard because they thought the trade-offs were worth it.
I agree with Lukas here, but I think there's more. Yes, having an input area which can be keyboard, canvas, or aircraft controls is alone enough justification for not including a physical keyboard when text-entry is not key. If you do *have* to type, a real keyboard wins.
BUT! The current iPhone (etc.) keyboard simply copies how mechanical keyboards work. Tap, tap, tap. Darn, I missed the G. The strength of a touchscreen is not its tap detection — if anything, that's the most unreliable part of the interaction. Trying to type fast on the iPhone is like trying to play 'Flight of the Bumblebee' on the Double Bass. Sure you can do it, but it's not a good match. Instead, I'm eagerly anticipating development in alternate touchscreen text-entry approaches combined with the addition of better touchscreens, haptic technologies and new sets of software idioms.
And I don't believe I'm the only one. I think Apple is predicting a near-term future where touchscreen text entry methods actually outperform full-size mechanical keyboards. And that this future is near enough to require them to commence the evolution of their technology, and their users, in order to get there. I believe the aping of the QWERTY physical keyboard is a transitional step.