As some are fond of saying about nearly anything, "It is just good insurance!"
It pays to remember that there are many areas of the country where cell service is spotty at best, non-existent at worst. Do not believe those maps where the cell company has an entire state painted in, particularly here in the West! It might not be entirely accurate!
As a licensed Amateur Radio Operator, I have an all-band, all mode 100 watt radio in the truck. If I had room (without hanging it from the roof) I would also have a CB in there! Maybe I'll get the one that has the box under the seat, and all the controls are on the mic.