The crap ships are the results of it spamming them early on, it doesn't seem to stop spamming them because it doesn't tech very well so it spams hundreds of them and doesn't really progress properly into creating more effective ships. It clearly techs the hulls but it still producing the large hull with basic 1 damage weapons.
I think the AI gets screwed with not knowing what to do with these ships, because most of the time they aren't capable of fighting the ships you're attacking with. It's like something is telling it to do two different things.
I've knocked on the AI's door really early on with a medium hull with ancient missile defence system that's 46 attack at the 1 damage stage of the game. It's decision seemed to be form small fleets near it with random singular ships and then attacking rather than group up properly then attacking. It's been told to soften the target until a fleet can finish the job or it's ship of the line can. It doesn't understand how to "soften up a target "properly though.
It can't drop the shields and focus the ancient missile system ship so it would have to attack it will lots of fleets in quick succession to stop it even then it would be a major maybe.
The only time I've really seen good ships out of the AI is in super long games, a few times with my custom factions and once with slynee which were I say moderately good ships.
Basically I think the AI acts the way it does because it know it's *******! It can't use the force, it can't fight those star destroyers and it can't repel firepower of that magnitude.