USB is also a crappy way to recharge things. It takes ages for the paltry USB power to recharge my smartphone, particularly if I don't turn the screen off (phone stays awake with USB attached)
USB doesn't really have anything to do with it, it's about the devices (both the phone and the charger). The specs say an USB charger can provide up to 5A, which is more than enough to reach the battery charging limits, AFAIK.
