Totally agree that the current traits should be revisited.
My biggest request would be to bring in a personality slider like in TS2, bring back favorites, and have the traits affect gameplay such as what @drakharis mentioned or even just like in the previous games where traits/personality would affect things like how fast or slow a Sim gained a skill or their ability to do one thing that another Sim with different personality couldn’t do.
What I think might also help is adding more slots for Traits and then changing how they organize and distribute the traits that we do have. In CAS, the traits are separated by Personality, Lifestyle, and the other one???Hobbies. What they could do is make the lifestyle and hobby ones more like favorites and interests in the previous games and add more Traits for the Personality category. And allow Sims to have more Personality traits in addition to the lifestyle and hobby traits.
But until traits actually affect gameplay beyond just moodlets, then it really doesn’t matter what they do.