Perhaps not useless, but definitely not as convenient as we hope warp technology will be someday. Could such a device be used as a way to improve thruster efficiency? If you can drag a large enough warp bubble with conventional thrusters, and it "slopes" space in front of you, could it make moving in the direction of the slope easier so you use less fuel?
I don't remember the details, but they explored some different field geometries which were more useful, but required an impossible amount of energy. Like, more energy than the entire universe.
