I'm guessing it probably has something to do with static buildup control. If you're pumping the fluid from metal through a rubber hose to more metal, maybe they were protecting against some kind of static buildup? Probably rare and plenty of places for it to dissipate, but cheap insurance.
Nope......Actually it is there to complete the ground circuit between the metal sending unit and the metal fuel line, which has the rubber fuel line between the two.
Remove this strap, and your gas gauge will not operate.