Just remembered a couple more.
The AI is too scraphappy. Why not mothball for later use? When production file calls for something check if it exists but is mothabelled and unmothball it if does.
It also scraps still useful ships to build bigger ships instead of keeping the smaller ships around and retrofitting them to keep up with technology.
I don't know if the AI retrofits at all, but if it does (haven't seen it), it doesn't do it enough as I often see AI fleets with a few brand spanking new ships and a bunch of old buckets of rust. If all ships (or a majority) had been upgraded to the latest and greatest it could have stood a chance in defeating me.
It also needs to build more storage facilities to store the resources it generates so it can upgrade ships and bases.
It also needs to get rid of old weapon platforms and build new ones either by spacing them or moving them to a big planet with lots of cargo space where they are not in the way. Best would be if we could scrap units to get resources back. The AI likes to scrap so that would be good. It often has alot of very old weapon platforms on it's planets late in the game that can't even fire at the enemy. Give them extra range like bases. To sats too but not as much.
Repair Ships. The AI needs to use repair ships. Badly.
Strategic combat AI when it comes to boarding. Boarding just doesn't work unless you control the boarding ships yourself. Even if you arm the boarding ships with shield busting weapons they hang way back from the action and only moves in when an enemy ships shields are down. Problem is 99 times out of a 100 that ship is destroyed before they get there which means they will move back out of range. I tend to build armed boarding ships that can take alot of beating capable of knocking down shields, not always with shield busting weapons (don't have them yet). They work perfectly in tactical when I can control them myself but in strategic they do ****. Even against an unarmed freighter with shields they are impotent in strategic. If armed they need to get in there and pound away and if not they need to designate a target ship for boarding (decided in strategy, highest tech, strongest, whatever (I'd like to be able to specify specific known enemy designs)) and when the shields of ships flagged for boarding are down the rest of the fleet should stop shooting at it. Both if the boarder is armed and helps bring the shields down or is unarmed and hangs back until they are down. And they should start moving in before the shields are down so the enemy ship doesn't fly around shooting for too long before it is boarded. Related: Self Destruct Device should not work if ship has no engines left (description says it overloads the engines. change desc. or function). Also, it should not automatically destroy the boarding ship. Way to powerful (10kT instnatly destroys ship some distance away, 50kT ramming charge doesn't automatically destroy ship upon contact at high speed?). Random amount of damage between a set min and max, yes, but not instant destruction imo.
That's it for now. Will undoubtedly come up with more.