AIP can be presented and explained better in AIW2, to help ease any issues. At its core, it works pretty well as-is though.
Agree with both keeping the concept and rising structure of AIP and the importance of presenting and explaining it as best we can.
One thing I would change is making the tech level steps less cliff-like and more gradual.
For newer players, I think the cliffs are a good idea, to emphasize just how important the AIP mechanic is. Newbies are not going to notice any subtle changes anyway. The rest of this applies to the power players:
I understand the representation of AIP as a number, the returned value from some mysterious unknowable alien subroutine. But must we humans always know exactly what the AIP value is and what the AI is most "worried" about?
Instead of +1 AIP every 10 minutes, what about 0, 1 or 2 AIP every 10 minutes, with an equal probability of each result? (Or 0, 1 or -1 AIP every one minute for an unstable AI?) The expected value of AIP remains the same, but the player's uncertainty increases a bit every time interval. So the AIP might be 5 plus-or-minus 1 after 10 minutes, but 120 plus-or-minus 18 after three hours. This really doesn't make the tech level steps more gradual, it just makes it easier for a player to trip on them in the dark.
Does this AI care more about losing ships or losing structures? Is it more threatened by damage from player raids or large concentrations of player ships? These kinds of things included in "AI Personalities" might give them more, um, personality.
(My mental model is from WWII board game World in Flames. As the Japanese player, you want to Pearl Harbor the United States just before they decide to enter on their own, but as in real life you can't tell precisely when that will be, merely a range of results.)
Maybe hacking can "gather intelligence" (shown by narrowing the AIP range) or de-sensitize the AI to some particular player action?