Because you don't know that you can just cut the data wires in a cheap USB cable, and want to be 'protected' by a cool hipster toy that'll sit in your laptop/phone baggie until you're at some party and can shout in triump when someone plugs in their phone 'just to charge': "NO, USE MY USB CONDOM!!"
EDIT: if this thing actually had some diagnostic LED's that would show you that the 'power port' was trying to do something nefarious on the data lines, it'd be a lot more useful than an ultra-cheap snipped cable imho ..
Sure. The advantage of this is you don't have to cut open one of your cables, you can easily (and visibly) decide whether you want the data pins connected or not and this works for any USB device, ie. USB micro as well as Apple and other proprietary connectors.
Everyone wants to reduce their risk, but not everyone wants (or is competent) to do surgery on a cable or terminator. And if you have a custom cable you like or a weird charge port on your device, you'll just want something you can interpose rather than a whole separate system.
