Why? There is a VUSB pin (1 wire) and one of the GND pins (1 wire) - no more
@ScruffR I guess USB connector was a bad choice of words.
@ScruffR when Rftop mentioned this he linked a micro-usb powered wall charger on Amazon. So I assumed when he said "USB connector" he meant the micro USB male plug and was suggesting me to use the micro header so I can just plug/unplug the device and then just solder the Vcc/gnd lines to my PSU. This does solve the "assembly problem as I don't have to solder directly to the particle pins. Cons is that this adds length to the board which I don't want since it won't fit in the enclosure I am using.
VBUS/VUSB pin is what I currently use now and is soldered to my PSU. That I agree is just 2 cables like you said 
Meh, faint hearted.... I guess I have a spare particle board, an RPi and a fire extinguisher. I'll build the binaries on my laptop, cloud flash the device and check the serial logs via a RPi for debugging. If it blows up at least I won't loose my laptop and will look into diodes and deactivating the Vcc line in the USB. Good suggestion!
I'm trying to fit the particle inside a standard 2 gang electrical box with some custom circuitry. This is a prototype for a company so I can't give any more information than that. I do need to make quite a few units for testing/development purposes so I am trying to simplify assembly. If this works out we will be looking at perhaps laying out a custom board. For now, yes "flying" wires...