Sims need to insert their OWN personality. Alongside player manipulation.

I'm not really disagreeing with you. I just think that sometimes too much autonomy will ruin a storytelling gameplay. For example, my sim is supposed to cheat with somebody else in my story but he insisted to be loyal with his partner, so I have no way to force romantic interactions with another sim but follow my sim's choice all the time.

My point is, instead of forcing Sims to have random autonomous personalities, it's better to have a toggle on/off for different types of players, just like how we are able turn on/off autonomy in the game now.