My first Technic set was the Backhoe, wich was loaded with pneumatic stuff and even had two pumps.
While i also prefer manual pump over pf-pump it makes more sense in a vehicle with suspension to use a powered one.
Imagine the Arocs, everything would wobble if the manual pump was on the truck itself. If it was built in one of the outriggers, to get a stable connection to the ground it would be okay i guess.