im actually surprised we haven't replaced nukes with ke weapons yet. you just need some satellites i high orbits to toss massive tungsten spikes at the target cities of the world. no warheads, just pure velocity, and only costs a heavy lift launch vehicle or 50. rods from god would take a cold war budget to install right now, and would require colonization of local space and asteroid mining to replace nukes. antimatter does pack some impressive energy density, the trouble of creating it and containing it would restrict its uses. there are much much more cheap and efficient ways to destroy stuff. im sure it might be useful as an anti-planet weapon.
consider the history of nuclear weapons. back in the 50s and 60s we had warheads in the megatons, these were common. but these have been replaced with warheads of a few kilotons. we have come to the conclusion that we no longer need a doomsday arsenal to provide an adequate nuclear deterrent. so we have scaled back our armament to levels where we can still cause critical damage to an enemy, but do it without crippling the whole planet in the process. our planet locked civilization has reached the maximum limit of sane firepower. the physical size of our civilization would need to expand a lot before we can justify creating bigger death machines. when that time comes, perhaps we can call on antimatter to make bigger warheads, and i can wank to the test detonation footage.
