This is something that's been annoying me for a while. While to an EXTENT it's something I'd try to do in the sense of grabbing juicy Class-10+ worlds in the middle of the AI's little civilization for the express purposes of denying them, I've never once actually thought about wasting the time and money to go obsessive-compulsive and try to scoop up every inane, class 4- world in the center of my opponent's civilization.
Simply put, these worlds are so insignificant that they don't have the resources to be any considerable value or hindrance to the enemy, and are so deep in enemy territory sometimes they'll just instantly revolt anyway.
Generally, once the AI has exhausted planets in their own system, they'll begin pouring colony ships into MY systems trying to grab these stupid little worlds. It's extremely irritating and unrealistic.
Scenario: I've conquered a little corner of space and have a conflicting border with the Altarians. They're doing pretty piss-poor and I'm ready to fill their space with electric death. I suddenly see an Altarian colony ship heading for my home world... for the Class 4 you start with that I usually never bother to grab. I watch with mild amusement as they take the world, and no more then 3 turns later, the planet is in a state of revolt due to its proximity with my homeworld. It turns over to me.
What the hell is wrong with the AI? Any planet worth wasting my time on I already took, leaving a few class 4 or smaller planets. I spy another colony ship, followed by another heading for various locales in my dominion. I get irritated and immediately turn a billion people into frozen, decompressed space debris. I begin invading Altarian space. And I watch as, in the middle of a WARZONE, they CONTINE to try to rush colony ships around my warships (to no avail) in a desperate attempt to grab laughably worthless Class 2 worlds. In fact, they're building more colony ships then military ships, and I'm wondering when they're going to run out of people.
In the end, they all died. The planets they 'stole' from me didn't even have a PURPOSE. They just built a factory and a starport if they had room, so it wasn't even some sort of influential strategy they were trying.
This happens every game, no matter against whom I'm playing. It'd REALLY make me happy if the AI could at least have a little update that would simply stop grabbing inane, shitty little planets in an enemy's influence. I don't understand what purpose it serves except to annoy me IMMENSELY and to exhibit a rather glaring flaw in the AI's "intelligence", since while rushing a colony ship into an opponent's neighborhood to grab a low-class planet isn't something I'd do too often, and while doing the same while it's in HOSTILE territory isn't something I'd do at ALL, and even were I so inclined, if said colony ship were destroyed EVERY TIME I TRY, I'd probably give it up in a hurry.
So to me, it makes no sense why the AI keeps doing it.
Wow, that was long.