AWESOME. that is a new fave strip! I love it. made my dad and it's only been 33 minutes.
Funny strip. But the real answer is:
a) The DC power connection in a car is used by people to power other things besides cell phones and ipods. Some of these things require more power than a USB connection can supply.
b) People making portable devices and adapters know that every car has at least one of these power connectors. Commonality of interface creates a lot of inertia that's difficult to overcome.
The Kia Rio I just rented has a USB port. It also has two cigarette lighter plugs with no cigarette lighters in them.
I installed on of these in my last car because it didn't have one. Had to power my amateur radio.
I have an aftermarket GPS which needs power and also my GF has an electrically heated (12 V) throw blanket she uses this time of year, because I.... "KEEP THE FREAKING CAR AS COLD AS ANTARCTICA! OMG, I CAN SEE MY BREATH!" when I drive either her sedan or my SUV. Heated seats apparently aren't enough for her in either vehicle. If the car or SUV is too warm, I get drowsy.