I feel that they never expected that an organized state fought back.

So long as these interceptions have to rely on physical ammunition and all of the limitations that entails the attacker will always have the advantage. If you can only launch X number of interceptors even if you have a 100% success rate all it takes to defeat it is launching X+Y missiles and you know Y number of missiles will get through. And since simple missiles are always going to be cheaper than expensive interceptors you're almost guaranteed to be able to defeat defence systems provided you have the capability to launch enough rockets

That´s the missile warfare equivalent of a meat wave attack: throw in more bodies than the enemy has bullets. Russian style.

Depends on the drone in question, and some people have developed "semi-decoys" that are basically fixed wing drones or cheap cruise missiles that have enough payload to not be ignorable but also are screens for the hypersonics and more powerful munitions.