Thankfully, modders can fix just about everything in the game at this point and a mod called More Traits in CASexists to save us all from these woes. Since games like The Sims 3 had 5 traits slots it really feels like a step back having only 3 for adult-aged sims in The Sims 4.
We really don’t have enough trait slots in the game for any sim’s life stage and this annoys me to a level I can’t even describe.