In 2.42, the AI is a pussycat until about AD1000! After that its like an angry kitten compared to MPG. Playing at diety level, in 2.42, you can form alliances with most of the AIs and maintain them for eons. Try that in MPG, and the AI attitude drops to hostile/enraged so fast it will make your head spin!
In 2.42, you can gift an AI civ to Cordial or higher, form an alliance, swap all its techs, swap maps, and get gifts. In MPG, its tough to get more than one or two allies, and they tend to go from enthusiastic to hostile in less than a turn.