If your bad guys can get high enough to sever your cable, they can get high enough to do a kinetic or powered bombardment and cause magnitudes more damage.
Plus accidents are more likely than you think. A rocket just exploded this morning, and read up on rates of railroad or shipping screwups. A train full of apples and pallets of kleenex going over ain't a big deal but the same containers falling out of the sky will certainly cause more damage.