Then it still doesn't make sense to me. I know that normally USB 3.0 ports transfers power through the same cable as the data is transfered by, but via separate wires within the cable. Since this card is PCIe, I would think the same thing would true, because even the molex connector on that card has to obtain power from the motherboard via it's PCIe connection.
Even if I am totally wrong about this, it is obvious that means of connecting would be useless for connecting an exterior peripheral, because the cable that some cards provide are only long enough to reach something inside the case. If an exterior device required power from the computer, instead of having it's own power adapter, it could be accomplished by using an separate back panel connector that acted as an intermediary device to relay internal power to an external cable going to an external peripheral device. Somehow that card's molex connection seems extraneous to me.
EDIT: Rereading what you said, I think that you are saying that cable and connector are to obtain power directly from the power supply, rather than the PCIe slot...yes?