They are also defending and don’t really have a choice, Russia does.

It kind of works. Imagine that Iran would be able to blow Amazon warehouses in the USA using drones after 4 years of fighting. Sure there would be few fanatics on Fox News wanting to nuke Iran, but most of people would be asking what is the point of bombing Iran in the first place? What's the goal?

Because that's what Russians are facing right now. No gas on gas stations. No online ordering of stuff. Enemy drones are flying daily over their heads after 4 years of fighting, Russians are fearing of another mobilization and for what? What is the goal of this war?

It rarely works (Mitchell and Douhet were famously proven wrong a few short years after WW1). But it is the named reason Kiev gives.

I think it's a matter of perspective. It's Russia's war. The Russian people didn't want this, but they have to live with their leader's decisions. For the Ukrainians, the alternative is surrendering to Putin.