I would rather have matches put under my fingernails than write a letter to my accountant on a 2.5 inch screen. And I can't think of a reason to carry arround a PC in my pocket, sensitive personal data and all. No, smart phones are not practical. Smart phones are in fact bought by the same gadget enthusiasts you dismissed as the only customers for weaktops
Smart phones are the moden equivalent of of the digital watch pen. Back in 1982 people would stand around in groups and go "oooooh!" when shown a pen with a digital watch built into the barrel. Useless of course, but they had that aura of desirability.
Weaktops, on the other hand, have a real market among middle-aged folks who want to store their photos, and a few music tracks, in a place where they are safe from the kids who have already monopolised and wrecked the family PC. And they can be used, at a pinch, for home office computing, most of which could be accomplished on a 486. Like writing a letter to my accountant, for example.
Smartphones - really interesting short term, completely useless
Weaktops - really rather usefull, completely boring
Oh and it was nice to see wheeled out that oft-repeated and most devastating of Linux counter-arguments, viz. that the sysadmin smells. I am a sysadmin and I am wearing an ironed shirt, Lynx deoderant and a rather nice pair of Loakes. I thank you.