Whoa, sorry you haven't gotten an answer on this.
Unfortunately this is necessary, and can't be hacked easily.
The back of the drive is just a SATA connector that connects to the internal SATA pins on the drive when plugged in.
To use wifi the satellite boots up small single-board computer (it's running an OMAP3 used on beagleboard and some Android phones). Since the internal processor is using the drive's SATA connector, you can't just go plugging it in to something else without disconnecting it from the internals first.
The only way I can think of to design around this would be to copy Android's solution and use USB MTP to access the drive. I doubt the pins are even accessible inside the device to solder this in, but you could probably convince a BeagleBone or RaspberryPi or something to serve up files like this with enough hacking. The drawbacks are that it would be USB 2.0 only and very slow, and you'd probably need to install drivers to get it to work at all.
Guessing Segate looked at their options and decided to go with the upgradable SATA dock for the fast, direct USB 3.0 access over being able to leave WiFi on.
