Wish there was a way to choose who took what role in interactions.

This reason is exactly why I want the personality traits to TRULY affect their behavior and have them do the same actions differently based on traits, instead of them just having "special" actions based on their traits. for example: a loner sim should appear withdrawn/less talkative and more awkward body language during a conversation, while the outgoing sim is extra loud and animated with big hand gestures and etc, instead of both being equally friendly in conversations. A romantic sim that's also clumsy shouldn't suddenly become suave and charming when flirting, it should also be an awkward but endearing interaction that fails more than it works on other sims. I really think TS4 failed big time with the whole "emotions" system. I would prefer the traits actually giving the characters, well, character...