Why would you buy one NOT to put the phone in ?
because its a BLUETOOTH phone cradle. For example, home > office is 2 miles, I make that trip 2 or 3 times a day, my iPhone is in a case, I'm hardly likely to take my phone out of its case and put it in the cradle for a 2 mile journey, hence no car kit for that journey. If i had the HFP I would have a car kit (because I could just leave the phone in my pocket and it will work)