Another thing is, not all people, despite the large number you see in public fiddling with cell phones, can throw money away on what it costs to have internet service on such devices. From what I've seen they're usually the types that already have inflated monthly calling/data plans and end up downgrading them out of budget constraints.
They are more the exception than the norm, and if they weren't, the economy would be better and we'd be back to most everyone affording net cell service as an addon to their desktops, vs as an alternative. Besides that, I can't imagine trying to intensely research something at length on the net using a mere cell phone keypad and tiny screen EVERY time you have a hard time finding info. No thanks.