I've been playing SoaSE since beta and I normally don't post or complain...mostly 
BUT, the I have found an AI magnet in every game I play (usually on hard, but I find the magnet works in every game no matter what the level). By magnet I mean that I know how to get the AI to focus on one system to the exclusion of all other systems.
Step one: Take over (via colonizers) the free crystal and/or ore asteroids at gas planets, unihabitale systems, etc.
Step two: Build a starbase or maintain a fleet there
Step three: Sit and wait; the AI nearest the system will continually send fleet after fleet to the same spot in an attempt to dislodge you from the free crystal/ore nodes.
Step four: Hold what you got and send a second fleet to pillage the AI systems. The AI will be so busy trying to take the system from you that it will ignore most everything else and will not even bother to attack you where it would hurt the most.
This to me is the sign of a flawed AI. Why are the free systems of so much value that the AI fixates on them to the exclusion of all else?
Yes, I use Entrenchment and yes it's fully up to date. I have not tested this without running Entrenchment, but I presume I would experience the same effect.
Perhaps Ironclad could look into this?
Thanks, and despite this AI flaw, I still love the game 
Cheers!
Arras