Alright, I'm not putting this in suggestions, because I'm not suggesting it, mainly opening the avenue for discussing. A debate about the subject at hand, if you will. Anywho, with that out of the way, I shall begin.
Well, as we all know, in the modern age with game AI, "difficulty levels" translates into a different way than it should. It's all fake difficulty from giving the AI access to resource cheats, construction speed buffs or just giving them free units. I'm sure a large majority of you would agree that this is an extremely cheap way of "adding challenge" to the game. Now here, we have Starfarer, a game that, for me, has the best AI I have seen in a bloody long time. AI that uses skill, rather than stat buffs to out-manoeuvre and at times out-think the player. Now, what if in the campaign startup/mission screen (both, obviously. But since it's two different screens, yadda yadda yadda) there was a set of buttons for the difficulty level (easy, medium, hard. Or however many is practical) with the AI being smarter/dumber depending on the option. So like in easy, the AI is a bit simpler in the way it goes about, makes more mistakes and crew for both the player and AI ships are one level down (Elite has the accuracy of Veteran, etc.). Conversely, the harder AI would be more punishing in regards to player mistakes and the gunnery AI is one level up.
I know this type of thing would take ages to properly implement, considering the amount of AI writing that would need to be done, so that's why it's not a suggestion. It's more food for thought and comparing ideas of what difficult AI should be, etc.
I've rambled enough, so I'll open up the discussion... now.
Spoiler
P.S. This is mostly a ramblish post, and I am sorry for that