Rods from God deliver the energy of about 12 tons of TNT.

For comparison:

The British used 12 ton "Tallboy" bombs, carried by Lancaster bombers, in WWII against submarine pens.

The "Little Boy" nuke delivered the energy of 15,000 tons of TNT.

Some modern ICBMs carry 10 warheads, each of which delivers the energy of 475,000 tons of TNT.

One benefit of dropping a tungsten telephone pole from orbit is that there's no good way to stop it, because its just a chunk of metal moving very fast. Hitting it with a missile might scratch the paint, but won't significantly alter its course.

The main drawback is the expense of getting them into orbit. Falcon 9 can lift 2 of them if the poles are cut in half to fit under the fairing, at a cost of about $70 million. That does not include rocket engines, fuel, and targeting computers needed to get those 2 tungsten rods out of space and onto target.