I've always thought that bombing the HQ to kill darbars is simply griefing.
"Yay, they can't see us, so we can roll bases with even less opposition!"
So, I have to resupply the HQ (fun!), play hide and seek to find the enemy, or maybe just log off.
Instead of the HQ turning the lights out, how about it disrupts the command structure (in a sense) by disabling base captures until repaired?
It would give even a heavily outnumbered country a chance to hold back the horde. If the hording country does it to the low populated country, it wouldn't be much of a difference.
However, the biggest difference would be the darbars would still work and people with a flattened HQ could still find and oppose the enemy, instead of the current method of upping at a flashing base and hoping it's not just a single con at the dar circle, just setting it off to send the enemy on a wild goose chase. In other words griefing.