AI crew members have been a popular request, but I do not think the players making this request have thought it through.
Most if not all these requests are based in the idea of wanting AI to help with the ship in PvP situations. In a perfect scenario the AI will do everything you want it to, bucket, repair, cannon, helm, defend ladders. How would you want the AI to be balance? In our perfect scenario we can assume Rare can balance the AI to whatever level they want, what would the skill level of this fictional AI be at? If we have the AI be balanced around the average level of a Sea of Thieves player, then we will have a group of people below that skill level complain about how their duo sloop can't beat a solo sloop with an AI because the AI is too good. Now that duo feels like they must sail on a larger ship with AI so that the AI can carry them. Players that depend on this same AI will have complaints that above average players are so much better than their AI companions so what is the point of having AI companions if they cannot compete with the players that they want the AI companions to defeat?
If we scale the AI skill up to defeat these above average players, then why would anyone choose to sail with someone that is under the skill level AI? New player groups that are starting out and playing with friends would get discouraged by how good the AI is and that it is unfair that the most optimal way to play is with AI and not their friends. "How are my friends and I supposed to do anything with all these solo galleons full of AI sinking us and taking our treasure?"
I get that people feel the "skill gap" when facing better players and don't like that feeling but when put in the same situation and the other "players" are AI will that be better? Two solos, new to the game, watching their AI crews fight eachother while having no idea what's going on? Who actually wants this? What exactly do you want your AI crew to actually be capable of for players to be satisfied with?