Yep, we had a grumble at work about this the other day.. Apple is quite blatant on nickel and diming accessories..
The two power specs are a bit different:
Firewire charging (AVIC, old style): 1.5A/25v
USB charging (iphone, new style): 500mA/5v
Apple did USB+Firewire charging in 2004. They discontinued Firewire charging in late 2005, about a month before the Z1 was released.
Probably just enough time for Pioneer to go "oh crap.."