Hmm... on close inspection my suspicion is correct. There is a hard distance where the ship quality drastically changes. I'm not good at estimating distance, so here's two pics in external camera mode. Note these are both in the SAME game session - the only difference is that one is a brief UP keystroke closer to the ship than the other. There is a huge difference:
Most noticably the ships lines change, almost becoming invisible and this might seem bad but it's actually because the AA is kicking in and they're getting blended, and since they're so thin it's normal for them to be hard to see. But when you see this in motion, it's a sharp and obvious change from bad to good when you cross the line.
It's pretty clear the AA just turns off for distant objects. Modders... you know this stuff way better than me. Are there two sets of ship textures, one for far away and one for up close? Perhaps the far off ones could be replaced en masse with the high-res ones, which would put a higher load on the system but it would allow AA to work, even if only for higher-end systems.
All that is easier to see if you crank up the gamma. On further inspection there seems to be four distinctly different detail levels, which are easier to see if you move away from the ship upward with the camera looking down on the deck. There could be more than four. It would be
great if someone could figure out how to replace those lower detail versions with the highest detail version so it just uses it all the time!
Update: I just tried all the AA compatibility modes in nHancer and it had no effect. The textures are just switching, and low res crap can't be AA'd to look better when it starts out as crap in the first place. I'd kill for a solution to this!