I'd like to make a suggestion: Please make the difficulty levels moddable, e.g. by exporting all difficulty modifiers to a text file.
It's not about the AI intelligence settings in the first place (the number from 1-128), but about its bonuses: It would be nice to have a direct way to change the difficulty settings, like changing the economy bonus the AI gets on a certain level or giving the player a handicap.
It would allow a lot of things like "Oh, I'd like to play somewhere between current Crippling and Masochistic", "I don't like the AI influence bonus on the high levels" or "I want to give the AI even more bonuses than it has on Suicidal".