This is true since, it was impossible to play with the code when TAM basic versions were released, thus impossible to change the way the AI does its job...
On the other side, the xml files are full of AI Weigths, wich I didn't know much about back then... What I basically did during the groundwork phase of TAM was to simply copy-paste entries and modifying the tags that we knew about... As for AI weigths, they mostly remained unchanged... Now these serve to establish the leaders personalities, the way the AIs build, use the civics, train units, etc, etc, and, obviously, carry diplomatic relations with others... As for ressources trading, it's the same...
As an example, consider the alchemist building...
<FlavorType>FLAVOR_GROWTH</FlavorType>
<iFlavor>3</iFlavor>
The main feature of this building is to boost science, while giving +2 unhealthyness to the city... Of course, reseaching more tends to make your civ grow and prosper... on the other side, a FLAVOR_SCIENCE entry should replace this one, or be added, with a higher weigth than GROWTH. I tend to prefer the 2d solution, as the more precise you are with the way you define a building for the AI, the more it will be build in the right time, by the right civs... Used alonside the LeaderheadInfo file (wich is basically a long list of more thant 50 weights per leader), these weigths and the ones of all other entries from civic choices to unit training, can do a basic job as to how the AI civs behave...
Now that we have the SDK, it could easily come to mind to insert a new kind of weight, let's say FLAVOR_CIVILIZED, wich could be used to reduce the importance of certain things (may it be ressource trading or religious converstion) for civs that were considered more "barbaric" at the time... With this, the Germanic tribes would then probably build Alchemist laboratories waaayyyy later than Egypt would , wich certainly makes sense, and would in fact slow down these civs...
In fact, TAM weigths all need to be re-examined and changed