at first, i also thought it was stupid that they required you to tether it to a blackberry. then i realized that i kind of like that fact that you don't need to buy two $80 / month data plans (though tethering a blackberry by bluetooth kills the battery) for each.
too bad the playbook was too little, too late, and too expensive. hope they take a cue from HP and drop the price massively to clear their inventory