Board Thread:Lore Discussion/@comment-5632187-20130119213241/@comment-18016240-20150612063619

It's pretty much stated that humanity is at it's core, dark. There's no light in humanity to be had without taking it out, which results in hollows.

The thing about the Bow of Want is probably more a reference to Nashandra's desire to control all things related to Souls, including powers that would be considered "light" based like lightning or fire.