It's a cheese descision. The devs had to pick between allowing PQ drop/Improvement destruction on failed invasions (and letting people ruin worlds with 1 troop), and only causing ill effects when it succeeds (and letting people have the bonus with no ill effects if they send just barely too few troops the first time). They picked the latter.

Citizen adrianschenk:
The DreadArchon makes a good point. I have found that careful evaluation of the
AI soldering tech level is crucial to effective invasion. I have suffered many
terrible defeats and destroyed many good planets due to poor pre-attack intel.
Good luck and good hunting.

That doesn't make any sense at all. So if I devastate half the planet with a mass driver but lose the ground war, all the devastation magically goes away?

I would've preferred it the other way. If your planet is undefended, you're pretty much at the enemy's mercy anyway. Even if they can't beat your ground troops with theirs, logically they should be able to blast the colony from orbit, even until it's slag if they have the time/money. It makes interplanetary war more badass, as it should be.

There's already reasons NOT to do this, as well. Master of Orion 2 had the bombardment-to-oblivion option, but I never wanted to use it much because it'd destroy buildings, and starting a colony over from scratch was a pain in the ass. (Plus, assimilated enemy colonists counted more than your own people for score, and killing them wasted yet more resources.) GalCiv 2 goes even farther here - there are unique projects/trade goods, and some tactics damage the planet quality as well, making the planet even less useful when you rebuild. GalCiv 2 even makes it less abusable, since you only get to use these tactics with a Transport (as opposed to MOO2, which allowed bombardment with ANY ship that had a weapon).

I don't know, Byram...I mean, during the attack, you get the bonus, which implies the tactic succeeded at what it was supposed to (disrupt the core, slam a rock into the colony, whatever).

This opens up an interesting line of thought, though. I wonder if it should be possible for the defender to COUNTER a tactic. Like if you use a Mass Driver, the defending civ could spend money on an attempt to intercept it. Or with an information attack, they could spend money to disrupt the signals or broadcast their own propaganda or whatever. Or maybe they could have original tactics, like putting mines in the atmosphere for the transports or something. (The Planetary Defense base already gives a bonus like this, but GalCiv 2 could've gone a lot farther in this direction.)

f I use your theory for WWII, then Germany lost the war and didn't do any material damage to Allies, is it right ?


now yer getting it.

There is a balance between realism and fun.

Of course, if North Korea launches nuclear missiles at the US and they either fail in flight or get shot down, the "planetary quality" of the US doesn't decrease, does it? The "special" attack failed completely.

Simply, the developers have introduced a fairly simple model for planetary warfare that is kept simple to eliminate easy exploits or cheese. Could someone come up with a more complex model that accounts for a partial effect of thes special attacks? Yes, but then it is much harder to program in such a way to prevent the exploits/cheese.

BoomFrog:

something like that I tried to tell