I never understand this kind of thing. It's like someone saying "I can never buy a Honda because it just can't tow all the things I tow on my farm, or drive through deep mud." But then he drives his F350 every day 30 miles and back from home to town to do errands and get groceries getting 12 miles to the gallon. Most people would (and do) get a efficient small car for that sort of thing.
The fact is, the iPad is mostly a content consumption product. It's REALLY REALLY good at being that. Sure you can get some things done on it, too, but that's clearly not the intent of this design. If you need power to crunch your data and be "300%+ more productive" then sure you need your F350 for the time and place where it's appropriate. The iPad isn't going to fully replace your desktop that you need to earn your living.
For a lot of people, this means they don't need the super expensive laptop to cover their bases. They can get the cheaper desktop, with more power and bigger screen, and then have an iPad to cover their mobile (and again 90% of the time doing content consumption) needs.
I suppose my post came off in the wrong way. I have nothing against the iPad per se, simply the concept of having it as a primary computing device. I have used one quite a bit, and it's a great device, however I would really rather not write long papers, do spreadsheets, etc with it. That's just not practical IMO. I do see your point of the full on computer not being fully necessary all the time though.
The average normal person should not be touch typing. Before computers, the majority of homes did not have a typewriter. Most businessman did not have a typewriter on their desk either (their secretaries did), and certainly not a keypunch machine. This keyboard everywhere UI has only been common for 3 decades and hopefully will be gone in a lot less than another 3 decades. The popular tablets (PalmPilot, iPad) are good first steps.
What's wrong with a keyboard or touch typing? I guess I don't see where you're going with this, as typing on a touch screen for long pieces of work or long periods of time is far less efficient. I see where the touch interface has its uses, but in some places it's just far less practical.