Many people think TS4 has too less traits and too less traits can choose, include me. I hope my sims have more personality. Unflirty and vegetarian could add in base game, some traits could available for lower age, only need some emotions details processing(such as snob available for child but snob child won't boring when watching others TV channels)
Here's some ideas
-Impatient: Conflicts with perfectionists. Sims take shorter to craft items and lower quality, they have same eating animation as gluttons, more often running to move. They receive negative moodlets when undertaking menial tasks, only if they have related traits(such as neat). They will become tense by repeated social interactions.
-Something I can think out all have similar in TS3
Some traits in TS3 could back or have similar(such as diva and self absorbed) in TS4, some traits could no conflict. Such as childish and goofball/snob, squeamish/love outdoor, klepto/good(I remember they're conflict), etc. If others are emotion reasons(mean/good=opposite to hypocrite, in TS3 they aren't conflict, only most mean interactions locked from them. You also can create a hypocrite in TS3), klepto and good haven't emotional conflict(or I don't know/wrong remember) and klepto is behavior, good is personality
Similarly, clumsy could available for child
Somethings about traits details could more improving. Such as only neat and squeamish will wash hands when use toilet(like TS3). Slob won't flush toilet is do very well.