While I do agree the AI should be tweaked for more threat assessment and take precedence for immediate threats versus lesser threats. The only thing I felt that was a touch wrong with the AI's target acquisition and response. I've a low level arcane character which I opted to pick a pet that has more melee combat features naturally to protect the character better, I use my arcane abilities to augment said creature as well.
So.. if I stand stationary and remain a non-threat (ie don't attack or cast vs monster) they ignore me, the moment I begin to cast a spell, suddenly I've become public enemy #1. Now the only thing I see wrong with this, is that by the time the spell casting is finished the creature has pretty much covered the ground to strike me, which A forces me to interrupt and run, or B hope my concentration level holds to make the spell and the spawn misses it's attack.
Now while this isn't necessarily a -BAD- thing I find it a touch unrealistic. How and why would the creature instantly know I'm casting at it until the spell effect has gone off and dmg has been inflicted? Premonition? Now perhaps this has more to do with the way an attack registers with the NWN combat engine, as I'm capable of slinging a stone or firing a crossbow bolt much faster and hit or miss the target. Though the creature does turn aggressively to charge me in the process of firing.
Either way I'm forced to hold and shoot or run and let my familiar/guardian chase the creature and hopefully kill it with an attack of opportunity.
I don't see the AC issue much of a big thing, though having read the post and replies somewhat I can find agreeable points to how it can seem silly in it's AC selection method. Just thought I'd share my observations on the AI concerning low level/low AC characters, I just hope my feedback isn't seen in a negative manner and is constructive to tweaking or such.
-Note- My observations could have been the result of server side lag on my client. Not entirely sure just yet.