The attacker already has an advantage if they're able to take out your defending ships and land as many troop transports as allowed by their logistics ability. Ideally you want for that to not happen, or for so few transports to get through that your troops can recover after each invasion.

If you play as the Terrans, for example, they have some great technologies that can help with fighting a defensive war. Fleet warp bubbles can make defence ships that ordinarily aren't very mobile (because they're packed with weapons) into an effective fighting force which you can scramble to intercept enemy fleets before they get near a colony. The higher your logistics ability, the more cost-effective this becomes (since it's basically like giving every ship in the fleet a free warp engine) and the harder it is for the enemy to beat you because you can rotate out your damaged ships and plug in reinforcements really quickly, while he has to trail all the way back home if he wants to make repairs.

I can't wait for Galciv 3 to have tactical ground combat, this way, it won't just be an automatic invasion/defense affair.

Why? Seems like this is just another game design choice. I've asked myself this same question quite a few times, but usually during a hot moment in a game that I forget by the time I get back to typing here.



Starstriker1 has a few interesting ideas, especially the notion of being able to spend money to lower the value of the conquest if you lose. I'd add a defensive form of Information Warfare also; it could cancel incoming Info Warfare or raise extra troops from those hillfolk tax evaders.

Re nuking your own people, I've barely ever played Evil, but I'm trying the Drengin in my current game and I would not hesitate to scorch some earth (& Drengin) to keep it from inferior hands. Then again, if I somehow thought the Drengin should be governed by a Star Democracy, the scorched earth story line would get messy for me...