I don't know if this is different in D.A..... but the computers really tick me off when I try to trade with them most of the deals they except are nowhere near an even trade, it's like giving them free stuff, unless you have a huge diplo. skill and reall good relation with that race.
Anyway, I was thinking that each race could be given a "generosity" factor, where as, the higher the generosity factor the less stubborn they will be in trade deals.
So, for instance the drengin would have nearly no generosity, taking only deals that benefit their side, while the drath would be huge charity orginizers.