Why? Big men are already near the rim. They rarely need to drive the ball. Plus successful driving requires good handling too.
Not always - for example with Outside tactics C and PF make even some shots from perimeter, so it prooves that they can get the ball not near the rim.... So if they get the ball there, there are several option how to continue: Pass, Throw or drive. That's why it is recommended for the Bigs to have at least JS at any level to nake at least something with the ball :)
My personal point of view is that it is much better to have PF with high Driving and JS - it will help really a lot in any case, but decent Handling is also needed as well as Pass :) So it is always difficult to find such multiskilled PF, but for C the situation is more simple - At least JS... Just in case of something... Pass is always good, others - good of there is some figures rather than 1, but no need to worry if there is nothing interesting there...