USB charging please dont make us use adapters.
The best thing is having two ways to charge the devie, via dedicated power port, and via USB.
is bad when a device only charge by USB, because this way, you have some troubles if you want to use the device with some usb accesories such pendrives, usb controller, etc, and at the same time charge the device. (typical usage when you connect your device to your TV, and work as an Android set top box)
Think in this situation. you want to play a Mame game on your TV. Connect a MicroUSB Hub, and plug a USB controller, USB mouse and USB keyboard on it.
Your device run with low battery power.
What you do in this situation if you only can charge via USB?
one alternative may be power supply the HUB, and with some lucky, the HUB charge the device too (but not always occur this)
the best choice is to plug the power charger in the specific port, and keep your USB Hub with all your devices connected (in fact, this is the way i use my devices)
in another hand, is bad when the device come only with power port to charge. I have my JXDS7800B that only charge via power port, and my charger broked, and i can?t charge this because i don?t have another charge with th same kind of connector. (well, i made a cable really, but normal users most probably will not create this cable)
the best choice is adding dedicated port for charging, but with the choice of charging via USB too.