I would favor bombing vs. ground units resulting in interdiction, too.
IMO the combat values of the bombed (by air and sea) units should be heavily lowered and if they are hit by any ground-unit during the same turn they should be destroyed (as if they were damaged by the bombardment), but I think that the interdiction modifier should be even harsher than the "damaged" modifier (maybe -2 like being destroyed).
In this way the unit would be more or less useless for combat (borken moral, disorganised, no supplies... well... interdicted

), but would only be destroyed if they are attacked by a ground unit during the same turn.
If no ground attack happens they are able to regain their organisation for the next turn.
And I think that militia units should be destroyed as before since it is much more likely that such units will break when they face heavy bombardment and cease to exist as a fighting force
IMO this would be a decent representation of the effect of airpower without making it to powerful.
CharonJr