There is more than one reason to have a powered USB hub over a non-powered one. If you have several devices to plug in and charge, a powered hub will not affect the performance of any of them. And if the devices operate on higher voltage, the need for a powered device gets bigger. External hard drives, printers, and scanners are a few devices of high voltage. Yet, you can have unpowered ones for keyboard, mouse, flash drives, and game controllers.