-Because loading up one of those jukeboxes with music is tedious... load up your iPod at home and just toss it in the car.
-Less stuff that has a chance of getting jacked.
-Because I wouldn't trust a HD in -30C weather espeically when I park outside.

 

Could easily take the hard drive inside if i wanted. It appears to go in and out just like a 6pack outta a changer.

As far as loading music, it's all drag and drop thru a USB 2.0 connection. Dunno how much simpler that can get.