I ain't never seen a 1/2 ton pickemup with an 8000 lb crane on it.  Can't really carry 500 gallons of fuel either.  Where is the air compressor?  Welder?  If I wanted to drag a trailer around all the time, I guess I could, but what's the point of that when a truck works so much better?

The purpose of the service truck is to actually FIX stuff, not stand around looking at it while you wait for the dealer to show up with his service truck to fix it for you.      I'll bet there are a lot of guys on here driving around in pickemup trucks which cost more then both of our service trucks put together, but I'm thinking we have considerably more capability when something needs service in the field.