It's mainly a case of leverage... Putting a 10 ton weight up high that will hit a target at mach 10 would be expensive but easily match a nuke but also allow intense penetration, or with a frangible tail could throw hundreds of fragments sideways around the impact site... Making it more precise would be possible with a small guidance computer and compressed gas jets.

I think that it is unlikely one will ever actually be used though. And knocking them out of the sky away from earth probably would not be very expensive either, compared to trying to shoot down hypersonic ballistic missiles