You know, I keep hearing this, but I do not understand how that is true. Were it true, you, being a slashdotter and thus years ahead would be composing this on a tablet. Apparently the soft-keyboard and such are no bother, nor is the lack of easy copy/paste functions.
Personally, I'm typing this on my workstation which will never, ever, ever leave my office. Nor should it. I create content and solve problems on it. People may later consume said content but if you want to actually get anything more serious than email done, you need a real computer.
Furthermore, could you imagine spending 8 hours a day on a tablet? That is a laughable suggestion. Given that unemployment is less than 50%, I suspect most people using computers for something other than leisure will still use a keyboard at some point during the day.